Monocyclic L-nucleosides, analogs and uses thereof

ABSTRACT

Novel monocyclic L-Nucleoside compounds have the general formula  
                 
 
     Embodiments of these compounds are contemplated to be useful in treating a wide variety of diseases including infections, infestations, neoplasms, and autoimmune diseases. Viewed in terms of mechanism, embodiments of the novel compounds show immunomodulatory activity, and are expected to be useful in modulating the cytokine pattern, including modulation of Th1 and Th2 response.

[0001] This application claims priority to provisional application No.60/028,585, filed Oct. 16, 1996 and international application no.PCT/US97/18767.

FIELD OF THE INVENTION

[0002] The present invention relates to the field of L-nucleosides.

BACKGROUND OF THE INVENTION

[0003] The last few decades have seen significant efforts expended inexploring possible uses of D-nucleoside analogs as antiviral agents.Some of this work has borne fruit, and a number of nucleoside analogsare currently being marketed as antiviral drugs, including the HIVreverse transcriptase inhibitors (AZT, ddI, ddC, d4T, and 3TC).

[0004] Nucleoside analogs have also been investigated for use as immunesystem modulators, (Bennet, P. A. et al., J. Med. Chem., 36 635, 1993),but again with less than completely satisfactory results. For example,guanosine analogs such as 8-bromo-, 8-mercapto-, 7-methyl-8-oxoguanosine(Goodman, M. G. Immunopharmacology, 21, 51-68, 1991) and7-thia-8-oxoguanosine (Nagahara, K. J. Med. Chem., 33, 407-415, 1990;U.S. Pat. No. 5,041,426) have been studied over the years for theirability to activate the immune system. These guanosine derivatives showexcellent antiviral and/or antitumor activity in vivo. But, theseC₈-substituted guanosines were unable to activate T-cells (Sharma, B. S.et al., Clin. Exp. Metastasis, 9, 429-439, 1991). The same was found tobe true with 6-arylpyrimidinones (Wierenga, W. Ann. N. Y. Acad. Sci.,685, 296-300, 1993). In other research, a series of 3-deazapurinenucleosides were synthesized and evaluated as immuno-modulating agents.U.S. Pat. No. 4,309,419 describes the use of 3-deazaadenosine as beingan inhibitor of the immune system. The ∃-D-nucleoside,∃-2′-deoxy-3-deazaguanosine (U.S. Pat. No. 4,950,647) displayed the mostpotent immunoenhancing potency on activated T-cell response.Antiinflamatory and immunosuppressant activity has also been disclosedfor certain 2′-deoxynucleosides (EPO Application 0 038 569). However,these compounds undergo facile in vivo metabolic cleavage of theirglycosyl bond, which effectively inactivates their biological potency.Adenosine derivatives disclosed in U.S. Pat. No. 4,148,888 are alsocatabolized in vivo by deaminase enzymes. In still other research,Levamisole, a thymomimetic immunostimulant (Hadden et al, Immunol.Today, 14, 275-280, 1993), appears to act on the T-cell lineage in amanner similar to thymic hormones. Tucaresol (Reitz et al, Nature, 377,71-75,1995), another T-cell stimulant, is now undergoing clinicaltrials. More recently, 6-substituted purine linker amino acid (Zacharieet al, J. Med. Che., 40, 2883-2894, 1997) has been described as apromising immunostimulant which may be targeted for those disease stateswhich require an increased CTL or Th1 type response.

[0005] One possible target of immunomodulation involves stimulation orsuppression of Th1 and Th2 lymphokines. Type I (Th1) cells produceinterleukin 2 (IL-2), tumor necrosis factor (TNF∀) and interferon gamma(IFN( ) and they are responsible primarily for cell-mediated immunitysuch as delayed type hypersensitivity and antiviral immunity. Type 2(Th2) cells produce interleukins, IL4, IL-5, IL-6, IL-9, IL-10 and IL-13and are primarily involved in assisting humoral immune responses such asthose seen in response to allergens, e.g. IgE and lgG4 antibody isotypeswitching (Mosmann, 1989, Annu Rev Immunol, 7:145-173). D-guanosineanalogs have been shown to elicit various effects on lymphokines IL-1,IL-6, IFN∀ and TNF∀ (indirectly) in vitro (Goodman, 1988, Int JImmunopharmacol, 10, 579-88) and in vivo (Smee et al., 1991, AntiviralRes 15: 229). However, the ability of the D-guanosine analogs such as7-thio-8-oxoguanosine to modulate Type I or Type 2 cytokines directly inT cells was ineffective or has not been described.

[0006] Significantly, most of the small molecule research has focused onthe synthesis and evaluation of D-nucleosides. This includes Ribavirin(Witkowski, J. T. et al., J. Med. Chem, 15, 1150, 1972), AZT (De Clercq,E. Adv. Drug Res., 17, 1, 1988), DDI (Yarchoan, R. et al., Science(Washington, D.C.), 245, 412, 1989), DDC (Mitsuya, H. et al., Proc.Natl. Acad. Sci. U. S. A., 83, 1911, 1986), d4T (Mansuri, M. M. et al.,J. Med. Chem, 32, 461, 1989) and 3TC (Doong, S. L. et al., Proc. Natl.Acad. Sci. U.S.A., 88, 8495-8599, 1991). In this handful of therapeuticagents, only 3TC which contains an unnatural modified L-ribose moiety,the enantiomer of natural D-ribose.

[0007] After the approval of 3TC by the FDA, a number of nucleosideswith the unnatural L-configuration were reported as having potentchemotherapeutic agents against immunodeficiency virus (HIV), hepatitisB virus (HBV), and certain forms of cancer. These include(−)-∃-L-1-[2-(hydroxymethyl)-1,3-oxathiolan-4-yl]-5-fluorocytosine (FTC;Furman, P. A., et al, Antimicrob. Agents Chemother., 36, 2686-2692,1992), (−)-∃-L-2′,3′-dideoxypentofuranosyl-5-flurocytosine (L-FddC;Gosselin, G., et al, Antimicrob. Agents Chemother., 38, 1292-1297,1994), (−)-∃-L-1-[2-(hydroxymethyl)-1,3-oxathiolan-4-yl]cytosine[(−)-OddC; Grove, K. L., et al, Cancer Res., 55, 3008-3011, 1995],2′,3′-dideoxy-∃-L-cystidine (∃-L-ddC; Lin, T. S., et al, J. Med Chem.,37, 798-803, 1994), 2′fluoro-5-methyl-∃-L-arabinofuranosyluracil(L-FMAU; U.S. Pat. No. 5,567,688),2′,3′-dideoxy-2′,3′-didehydro-∃-L-cystidine (∃-L-d4C; Lin, T. S., et al,J. Med. Chem., 39, 1757-1759, 1996),2′,3′-dideoxy-2′,3′-didehydro-∃-L-5-fluorocystidine (∃-L-Fd4 C; Lin, T.S., et al, J. Med. Chem., 39, 1757-1759, 1996), L-cyclopentylcarbocyclic nucleosides (Wang, P., et al, Tetrahedron Letts., 38,4207-4210, 1997) and variety of9-(2′-deoxy-2′-fluoro-∃-L-arabinofuranosyl)purine nucleosides (Ma, T.'et al, J. Med. Chem, 40, 2750-2754, 1997).

[0008] Other research on L-nucleosides has also been reported. U.S. Pat.No. 5,009,698, for example, describes the synthesis and use ofL-adenosine to stimulate the growth of a plant. WO 92/08727 describescertain L-2′-deoxyuridines and their use for treating viruses. Spadari,S., et al, J. Med. Chem., 35, 4214-4220, 1992, describes the synthesisof certain L-∃-nucleosides useful for treating viral infectionsincluding Herpes Simplex Virus Type I. U.S. Pat. No. 5,559,101 describesthe synthesis of ∀- and ∃-L-ribofuranosyl nucleosides, processes fortheir preparation, pharmaceutical composition containing them, andmethod of using them to treat various diseases in mammals. A Germanpatent (De 195 18 216) describes the synthesis of2′-fluoro-2′-deoxy-L-∃-arabinofuranosyl pyrimidine nucleosides. U.S.Pat. Nos. 5,565,438 and 5,567,688 describe the synthesis and utility ofL-FMAU. WO Patent 95/20595 describes the synthesis of2′-deoxy-2′-fluoro-L-∃-arbinofuranosyl purine and pyrimidine nucleosidesand method of treating HBV or EBV. U.S. Pat. No. 5,567,689 describesmethods for increasing uridine levels with L-nucleosides. WO patent96/28170 describes a method of reducing the toxicity of D-nucleosides byco-administering an effective amount of L-nucleoside compounds.

[0009] Significantly, while some of the known L-nucleosides have shownpotent antiviral activity with lower toxicity profiles than theirD-counterparts, none of these L-nucleoside compounds have been shown toposses immunomodulatory properties. Moreover, at present there is noeffective treatment for the modulation of the immune system wherelymphokine profiles (Th1 and Th2 subsets) have been implicated. Thus,there remains a need for novel L-nucleoside analogs, especially a needfor L-nucleoside analogs which modulate the immune system, and mostespecially L-nucleoside analogs which specifically modulate Th1 and Th2.

BRIEF DESCRIPTION OF THE INVENTION

[0010] The present invention is directed to novel L-nucleosidecompounds, their therapeutic uses and synthesis.

[0011] In one aspect of the invention, novel L-nucleoside compounds areprovided according to the following formula:

[0012] wherein:

[0013] A is independently selected from N or C;

[0014] B, C, E, F are independently selected from CH, CO, N, S, Se, O,NR¹, CCONH₂, CCH₃, C-R² or P; R¹ is independently H, lower alkyl, loweralkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinyl or loweralkyl aryls. R² is independently H, OH, halogens, CN, N₃, NH₂, C(—O)NH₂,C(═S)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, lower alkyl, loweralkylamines, lower alkyl alkenyl, lower alkyl vinyl, lower alkyl arylsor substituted heterocycles;

[0015] D is independently selected from CH, CO, N, S, Se, O, NR¹,CCONH₂, CCH₃, C-R², P or nothing, where R¹ is independently H, O, loweralkyl, lower alkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinylor lower alkyl aryls, and R² is independently H, OH, halogens, CN, N₃,NH₂, lower alkyl, lower alkylamines, lower alkyl alkenyl, lower alkylvinyl, lower alkyl aryls or substituted heterocycles;

[0016] X is independently O, S, CH₂ or NR; where R is COCH₃;

[0017] R₁ and R₄ are independently selected from H, CN, N₃, CH₂OH, loweralkyl and lower alkyl amines;

[0018] R₂, R₃, R₅, R₆, R₇ and R₈, are independently selected from H, OH,CN, N₃, halogens, CH₂OH, NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl,lower alkyl, lower alkyl amines and substituted heterocycles; and

[0019] R₁, R₂, R₃, R₄, R₅, R₆, R₇ and R₈ are not all substituted at thesame time; such that

[0020] when R₂═R₃═H, then R₇ and R₈ are hydrogens or nothing;

[0021] when R₁, R₄ or R₅ are substituted, then R₇═R₈═H and R₂═R₃═OH;

[0022] when R₂ or R₃ are substituted, then R₇ and R₈ are H or OH;

[0023] when R₇ or R₈ are substituted, then R₂ and R₃ are H or OH;

[0024] when R₇ and R₈ are hydroxyl, then R₂ and R₃ are not OH;

[0025] when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH orC-substituted; F═CH; X═O, S or CH₂, then R₂ will not be H, OH, CH₃,halogens, N₃, CN, SH, SPh, CH₂OH, CH₂OCH₃, CH₂SH, CH₂F, CH₂N₃, aryl,aryloxy or heterocycles;

[0026] when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH, C-CH₃ orhalogen; F═CH; X═N—COCH₃, then R₂ will not be H or OH;

[0027] when A═N; B═CH; C═CH or CH₃; D═CH or C—CH₃; E is CH, C—CH₃ orC—CONH₂; F═CH; X═O, or CH₂, then R₂ will not be H or OH;

[0028] when A═N; B═N, CO or CH; C═CH, C—Cl or C—OCH₃; D═CH or C—Ph; E isCH, C—Cl or C—Ph; F═N or CO; X═O, then R₂ will not be H or OH;

[0029] when A═N; B═CO or CS; C═N or NH; D═CO or C—NH₂; E is CH or N; F═Nor CH; X═O, then R₂ will not be H or OH; and

[0030] when A═C; B═CH; C═NH; D═CO, CS or C—NH₂; E is N or NH; F═CO orCH; X═O, then R₂ will not be H or OH.

[0031] In one class of preferred embodiments of the invention, thecompound comprises a ribofuranosyl moiety, and in a particularlypreferred embodiment the compound comprises L-Ribavirin.

[0032] In another aspect of the invention, a pharmaceutical compositioncomprises a therapeutically effective amount of a compound of Formulas 1and 3-5, or a pharmaceutically acceptable ester or salt thereof admixedwith at least one pharmaceutically acceptable carrier.

[0033] In yet another aspect of the invention, a compound according toFormulas 1 and 3-5 is used in the treatment of any condition whichresponds positively to administration of the compound, and according toany formulation and protocol which achieves the positive response. Amongother things it is contemplated that compounds of Formula I may be usedto treat an infection, an infestation, a cancer or tumor or anautoimmune disease.

BRIEF DESCRIPTION OF THE FIGURES

[0034] FIGS. 1-12 are schematic representations of synthetic chemicalsteps which may be used to prepare compounds in the examples sectionbelow.

[0035] FIGS. 13-14 are graphical representations of the effect ofD-Ribavirin and L-Ribavirin on IL-2 TNFα, IFN-γ, IL-4 and IL-5 levels ofactivated T-cells.

[0036]FIG. 15 is a graphical representation of the effects ofL-Ribavirin on the inflammatory ear response to dinitrofluorobenzene.

[0037] FIGS. 16-26 are schematic representations of synthetic chemicalsteps which may be used to prepare compounds in the examples sectionbelow.

DETAILED DESCRIPTION

[0038] Where the following terms are used in this specification, theyare used as defined below.

[0039] The term “nucleoside” refers to a compound composed of anypentose or modified pentose moiety attached to a specific position of aheterocycle or to the natural position of a purine (9-position) orpyrimidine (1-position) or to the equivalent position in an analog.

[0040] The term “nucleotide” refers to a phosphate ester substituted onthe 5′-position of a nucleoside.

[0041] The term “heterocycle” refers to a monovalent saturated orunsaturated carbocyclic radical having at least one hetero atom, such asN, O or S, within the ring each available position of which can beoptionally substituted, independently, with, e.g., hydroxy, oxo, amino,imino, lower alkyl, bromo, chloro and/or cyano. Included within thisclass of substituents are purines, pyrimidines.

[0042] The term “purine” refers to nitrogenous bicyclic heterocycles.

[0043] The term “pyrimidine” refers to nitrogenous monocyclicheterocycles.

[0044] The term “D-nucleosides” that is used in the present inventiondescribes to the nucleoside compounds that have a D-ribose sugar moiety(e.g., Adenosine).

[0045] The term “L-nucleosides” that is used in the present inventiondescribes to the nucleoside compounds that have an L-ribose sugarmoiety.

[0046] The term “L-configuration” is used throughout the presentinvention to describe the chemical configuration of the ribofuranosylmoiety of the compounds that is linked to the nucleobases. TheL-configuration of the sugar moiety of compounds of the presentinvention contrasts with the D-configuration of ribose sugar moieties ofthe naturally occurring nucleosides such as cytidine, adenosine,thymidine, guanosine and uridine.

[0047] The term “C-nucleosides” is used throughout the specification todescribe the linkage type that formed between the ribose sugar moietyand the heterocyclic base. In C-nucleosides, the linkage originates fromthe C-1 position of the ribose sugar moiety and joins the carbon of theheterocyclic base. The linkage that forms in C-nucleosides are carbon tocarbon type.

[0048] The term “N-nucleosides” is used throughout the specification todescribe the linkage type that formed between the ribose sugar moietyand the heterocyclic base. In N-nucleosides, the linkage originates fromthe C-1 position of the ribose sugar moiety and joins the nitrogen ofthe heterocyclic base. The linkage that forms in N-nucleosides arecarbon to nitrogen type.

[0049] The term “protecting group” refers to a chemical group that isadded to, oxygen or nitrogen atom to prevent its further reaction duringthe course of derivatization of other moieties in the molecule in whichthe oxygen or nitrogen is located. A wide variety of oxygen and nitrogenprotecting groups are known to those skilled in the art of organicsynthesis.

[0050] The term “lower alkyl” refers to methyl, ethyl, n-propyl,isopropyl, n-butyl, t-butyl, i-butyl or n-hexyl. This term is furtherexemplified to a cyclic, branched or straight chain from one to sixcarbon atoms.

[0051] The term “aryl” refers to a monovalent unsaturated aromaticcarbocyclic radical having a single ring (e.g., phenyl) or two condensedrings (e.g., naphthyl), which can optionally be substituted withhydroxyl, lower alky, chloro, and/or cyano.

[0052] The term “heterocycle” refers to a monovalent saturated orunsaturated carbocyclic radical having at least one hetero atom, such asN, O, S, Se or P, within the ring, each available position of which canbe optionally substituted or unsubstituted, independently, with e.g.,hydroxy, oxo, amino, imino, lower alkyl, bromo, chloro, and/or cyano.

[0053] The term “monocyclic” refers to a monovalent saturatedcarbocyclic radical having at least one hetero atom, such as ON, S, Seor P, within the ring, each available position of which can beoptionally substituted, independently, with a sugar moiety or any othergroups like bromo, chloro and/or cyano, so that the monocyclic ringsystem eventually aromatized [e.g., Thymidine;1-(2′-deoxy-∃-D-erythro-pentofuranosyl)thymine].

[0054] The term “immunomodulators” refers to natural or syntheticproducts capable of modifying the normal or aberrant immune systemthrough stimulation or suppression.

[0055] The term “effective amount” refers to the amount of a compound offormula (I) which will restore immune function to normal levels, orincrease immune function above normal levels in order to eliminateinfection.

[0056] The compounds of Formula I may have multiple asymmetric centers.Accordingly, they may be prepared in either optically active form or asa racemic mixture. The scope of the invention as described and claimedencompasses the individual optical isomers and non-racemic mixturesthereof as well as the racemic forms of the compounds of Formula I.

[0057] The terms “∀” and “∃” indicate the specific stereochemicalconfiguration of a substituent at an asymmetric carbon atom in achemical structure as drawn. The compounds described herein are all inthe L-furanosyl configuration.

[0058] The term “enantiomers” refers to a pair of stereoisomers that arenon-superimposable mirror images of each other. A mixture of a pair ofenantiomers, in a 1:1 ratio, is a “racemic” mixture.

[0059] The term “isomers” refers to different compounds that have thesame formula. “Stereoisomers” are isomers that differ only in the waythe atoms are arranged in space.

[0060] A “pharmaceutically acceptable salts” may be any salts derivedfrom inorganic and organic acids or bases.

[0061] Compounds of the present invention are named according to theconvention of Formula II:

[0062] Compounds

[0063] The compounds of the present invention are generally described byFormula I. There are, however, several subsets of compounds which are ofparticular interest, including compounds according to Formulas III, IVand V below.

[0064] Compounds according to Formula III have the following structure:

[0065] wherein:

[0066] X is independently O, S, CH₂ and NR, where R is COCH₃;

[0067] R′ and R″ are independently selected from H, CN, C(═O)NH₂, NH₂,C(═S)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, heterocycles, halogens,lower alkyl or lower alkyl aryl;

[0068] R₁ and R₄ are independently selected from H, CN, N₃, CH₂OH, loweralkyl or lower alkyl amines; and

[0069] R₂, R₃, R₅, R₆, R₇ and R₈ are independently selected from H, OH,CN, N₃, halogens, CH₂, OH, NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl,lower alkyl, lower alkyl amines or substituted heterocycles; such that

[0070] when R₂═R₃═H, then R₇ and R₈ are hydrogens or nothing.

[0071] In compounds of Formula III, R′ preferably carboxamide or CN andR″ is hydrogen or halogens; R₁═R₄═R₅═R₇═R₈═H and R₂═R₃═OH, andpreferably X is oxygen.

[0072] Compounds according to Formula IV have the following structure:

[0073] wherein:

[0074] A is independently selected from N or C;

[0075] B, C, E and F are independently selected from CH, CO, N, S, Se,O, NR¹, CCONH₂, CCH₃, C—R² or P; R¹ is independently H, lower alkyl,lower alkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinyl orlower alkyl aryls. R² is independently H, OH, halogens, CN, N₃, NH₂,C(═O)NH₂, C(═S)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, lower alkyl,lower alkylamines, lower alkyl alkenyl, lower alkyl vinyl, lower alkylaryls or substituted heterocycles;

[0076] X is independently O, S, CH₂ or NR; where R is COCH₃;

[0077] R₁ and R₄ are independently selected from H, CN, N₃, CH₂OH, loweralkyl or lower alkyl amines; and

[0078] R₂, R₃, R₅, R₆, R₇ and R₈ are independently selected from H, OH,CN, N₃, halogens, NH₂, CH₂OH, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl,allyl, lower alkyl, lower alkyl amines or substituted heterocycles; suchthat

[0079] when R₂═R₃═H, then R₇ and R₈ are hydrogens or nothing;

[0080] when A is carbon; B═E═N; C is N—Ph, then F is not CH;

[0081] when A═N; C is CH; B═E═C—CH₃, then F is not nitrogen; and

[0082] when A is carbon, B═N; C═C—CONH₂; E═CH; F═S, then X is not CH₂.

[0083] In compounds of Formula IV, R¹ is preferably H, lower alkyl orallyl; R² is preferably H, OH, halogens, CN, N₃, NH₂, C(═O)NH₂,C(═S)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂ or C(═NH)OMe; and whenR₁═R₄═R₅═R₇═R₈═H, then preferably R₂═R₃═OH and preferably X is oxygen.

[0084] Compounds according to Formula V have the following structure:

[0085] wherein:

[0086] A is independently selected from N or C;

[0087] B, C, E, F are independently selected from CH, CO, N, S, Se, O,NR¹, CCONH₂, CCH₃, C—R² or P; R¹ is independently H, lower alkyl, loweralkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinyl or loweralkyl aryls. R² is independently H, OH, halogens, CN, N₃, NH₂, C(═O)NH₂,C(═S)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, lower alkyl, loweralkylamines, lower alkyl alkenyl, lower alkyl vinyl, lower alkyl arylsor substituted heterocycles;

[0088] D is independently selected from CH, CO, N, S, Se, O, NR¹,CCONH₂, CCH₃, C—R², P or nothing; R¹ is independently H, O, lower alkyl,lower alkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinyl orlower alkyl aryls. R² is independently H, OH, halogens, CN, N₃, NH₂,lower alkyl, lower alkylamines, lower alkyl alkenyl, lower alkyl vinyl,lower alkyl aryls or substituted heterocycles;

[0089] X is independently O, S, CH₂ or NR where R is COCH₃;

[0090] R₁ and R₄ are independently selected from H, CN, N₃, CH₂OH, loweralkyl and lower alkyl amines; and

[0091] R₂, R₃, R₅, R₆, R₇ and R₈ are independently selected from H, OH,CN, N₃, halogens, CH₂OH, NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl,lower alkyl, lower alkyl amines and substituted heterocycles; such that

[0092] when R₂═R₃═H, then R₇ and R₈ are hydrogens or nothing.

[0093] when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH orC-substituted; F═CH; X═O,S or CH₂, then R₂ will not be H, OH, CH₃,halogens, N₃, CN, SH, SPh, CH₂OH, CH₂OCH₃, CH₂SH, CH₂F, CH₂N₃, aryl,aryloxy or heterocycles.

[0094] when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH, C—CH₃ orhalogen; F═CH; X═N—COCH₃, then R₂ will not be H or OH;

[0095] when A═N; B═CH; C═CH or CH₃; D═CH or C—CH₃; E is CH, C—CH₃ orC—CONH₂; F═CH; X═O or CH₂, then R₂ will not be H or OH;

[0096] when A═N; B═N, CO or CH; C═CH, C—Cl or C—OCH₃; D═CH or C—Ph; E isCH, C—Cl or C—Ph; F═N or CO; X═O, then R₂ will not be H or OH;

[0097] when A═N;B═CO or CS; C═N or NH; D═CO or C—NH₂; E is CH or N;F═Nor CH; X═O, then R₂ will not be H or OH; and

[0098] when A═C; B═CH; C═NH; D═CO, CS or C—NH₂; E is N or NH; F═CO orCH; X═O, then R₂ will not be H or OH.

[0099] A particular class of compounds contemplated herein includesnucleoside analogs having a ribofuranosyl moiety where the sugar has anL-configuration rather than the natural D-configuration. This classincludes compounds which contain modified natural nucleic acid basesand/or synthetic nucleoside bases like triazole,3-cyano-1,2,4-triazol-3-carboxylate, 3-bromo-5-nitro-1,2,4-triazole,imidazole, 2-nitroimidazole,2-bromo-4(5)-aminoimidazole, pyrazole,3(5)-aminopyrazole-4-carboxamide, triazines, pyrrole, pyridine,azapyridine, thiazole, 1,2,5-thiadiazole, selenadiazole,4-amino-1,2,5-thiadiazole-3-carboxylic acid, methyl4-oxo(5H)-1,2,5-thiadiazole-3-carboxylate,4-amino-1,2,5-selenadiazole-3-carboxylic acid, tetrazole, azaphophole,4-amino-1,3-azaphosphole-5-carbonitrile,4-bromo-1,3-azaphosphole-5-crbonitrile, 2-aminophosphine-3-carbonitrile,methyl 2-amino-3-cyano -phosphole-4-carboxylate,4,5-dicyano-1,3-diazaphophole, diazaphophole, isooxazole,3-oxo(2H)-isothiazole-3-carboxylic acid,5-amino-3-chloroisothiazole-4-carbonitrile,5-methylthio-3-oxo(2H)-isothiazole-4-carbonitrile, isothiazole,pyrimidine and other substituted derivatives of these bases. Compoundsof this class may also contain independently other hetero-monocyclicbases and their derivatives, certain modifications of the ribofuranosylmoiety, and both N- and C-linked L-nucleosides.

[0100] Especially preferred compounds in this class include L-Ribavirin,1-∃-L-ribofuranosyl -1,2,4-triazole-3-carboxamide. L-Ribavirin isdescribed by Figure: where A, B and E are nitrogen; C is C—C(O)NH₂; D isnothing; F is CH; X is oxygen; R₁, R₄, R₅, R₇ and R₈ are hydrogens; andR₂, R₃, and R₆ are hydroxyl.

[0101] Ribavirin (1-∃-D-ribafuranosyl-1,2,4-triazole-3-carboxamide) is amonocyclic synthetic D-nucleoside that has been demonstrated activityagainst variety of viral diseases (Huffman et al, Antimicrob. AgentsChemother., 3, 235, 1975; Sidwell et al, Science, 177, 705, 1972) andcurrently undergoing clinical trials in combination with (-interferonfor the treatment of Hepatitis C virus. In the past two decades, avariety of Ribavirin D-nucleoside analogs have been explored and many ofthem exhibit the exceptional antiviral and antitumor activities.However, no work has been reported on the synthesis of L-isomer ofRibavirin analogs and their biological activity. In single crystal X-rayanalysis Ribavirin resemble structurally to guanosine (Prusiner et al.,Nature, 244, 116, 1973). Because of the resemblance of Ribavirin toguanosine, we expected that Ribavirin nucleoside analogs should showsimilar or superior immuno-modulating activity than guanosine analogs(Robins et al, U.S. Pat. No. 5,041,426) in addition to the antiviralactivity.

[0102] Uses

[0103] It is contemplated that the compounds of the present inventionwill used to treat a wide variety of conditions, and in fact anycondition which responds positively to administration of one or more ofthe compounds. Among other things it is specifically contemplated thatcompounds of the invention may be used to treat an infection, aninfestation, a cancer or tumor or an autoimmune disease.

[0104] Infections contemplated to be treated with the compounds of thepresent invention include respiratory syncytial virus (RSV), hepatitis Bvirus (HBV), hepatitis C virus (HCV), herpes simplex type 1 and 2,herpes genitalis, herpes keratitis, herpes encephalitis, herpes zoster,human immunodeficiency virus (HIV), influenza A virus, hantann virus(hemorrhagic fever), human papilloma virus (HPV), measles and fungus.

[0105] Infestations contemplated to be treated with the compounds of thepresent invention include protozoan infestations, as well as helminthand other parasitic infestations.

[0106] Cancers or tumors contemplated to be treated include those causedby a virus, and the effect may involve inhibiting the transformation ofvirus-infected cells to a neoplastic state, inhibiting the spread ofviruses from transformed cells to other normal cells and/or arrestingthe growth of virus-transformed cells.

[0107] Autoimmune and other diseases contemplated to be treated includearthritis, psoriasis, bowel disease, juvenile diabetes, lupus, multiplesclerosis, gout and gouty arthritis), rheumatoid arthritis, rejection oftransplantation, allergy and asthma.

[0108] Still other contemplated uses of the compounds according to thepresent invention include use as intermediates in the chemical synthesisof other nucleoside or nucleotide analogs which are, in turn, useful astherapeutic agents or for other purposes.

[0109] In yet another aspect, a method of treating a mammal comprisesadministering a therapeutically and/or prophylactically effective amountof a pharmaceutical containing a compound of the present invention. Inthis aspect the effect may relate to modulation of some portion of themammal's immune system, especially modulation of lymphokines profiles ofTh1 and Th2. Where modulation of Th1 and Th2 lymphokines occurs, it iscontemplated that the modulation may include stimulation of both Th1 andTh2, suppression of both Th1 and Th2, stimulation of either Th1 or Th2and suppression of the other, or a bimodal modulation in which oneeffect on Th1/Th2 levels (such as generalized suppression) occurs at alow concentration, while another effect (such as stimulation of eitherTh1 or Th2 and suppression of the other) occurs at a higherconcentration.

[0110] In general, the most preferred uses according to the presentinvention are those in which the active compounds are relatively lesscytotoxic to the non-target host cells and relatively more activeagainst the target. In this respect, it may also be advantageous thatL-nucleosides may have increased stability over D-nucleosides, whichcould lead to better pharmacokinetics. This result may attain becauseL-nucleosides may not be recognized by enzymes, and therefore may havelonger half-lives.

[0111] It is contemplated that compounds according to the presentinvention will be administered in any appropriate pharmaceuticalformulation, and under any appropriate protocol. Thus, administrationmay take place orally, parenterally (including subcutaneous injections,intravenous, intramuscularly, by intrastemal injection or infusiontechniques), by inhalation spray, or rectally, topically and so forth,and in dosage unit formulations containing conventional non-toxicpharmaceutically acceptable carriers, adjuvants and vehicles.

[0112] By way of example, it is contemplated that compounds according tothe present invention can be formulated in admixture with apharmaceutically acceptable carrier. For example, the compounds of thepresent invention can be administered orally as pharmacologicallyacceptable salts. Because the compounds of the present invention aremostly water soluble, they can be administered intravenously inphysiological saline solution (e.g., buffered to a pH of about 7.2 to7.5). Conventional buffers such as phosphates, bicarbonates or citratescan be used for this purpose. Of course, one of ordinary skill in theart may modify the formulations within the teachings of thespecification to provide numerous formulations for a particular route ofadministration without rendering the compositions of the presentinvention unstable or compromising their therapeutic activity. Inparticular, the modification of the present compounds to render themmore soluble in water or other vehicle, for example, may be easilyaccomplished by minor modifications (salt formulation, esterification,etc.) which are well within the ordinary skill in the art. It is alsowell within the ordinary skill of the art to modify the route ofadministration and dosage regimen of a particular compound in order tomanage the pharmacokinetics of the present compounds for maximumbeneficial effect in patients.

[0113] In certain pharmaceutical dosage forms, the pro-drug form of thecompounds, especially including acylated (acetylated or other)derivatives, pyridine esters and various salt forms of the presentcompounds are preferred. One of ordinary skill in the art will recognizehow to readily modify the present compounds to pro-drug forms tofacilitate delivery of active compounds to a target site within the hostorganism or patient. One of ordinary skill in the art will also takeadvantage of favorable pharmacokinetic parameters of the pro-drug forms,where applicable, in delivering the present compounds to a targeted sitewithin the host organism or patient to maximize the intended effect ofthe compound.

[0114] In addition, compounds according to the present invention may beadministered alone or in combination with other agents for the treatmentof the above infections or conditions. Combination therapies accordingto the present invention comprise, the administration of at least onecompound of the present invention, or a functional derivative thereof,and at least one other pharmaceutically active ingredient. The activeingredient(s) and pharmaceutically active agents may be administeredseparately or together and when administered separately this may occursimultaneously of separately in any order. The amounts of the activeingredient(s) and pharmaceutically active agent(s) and the relativetimings of administration will be selected in order to achieve thedesired combined therapeutic effect. Preferably the combination therapyinvolves the administration of one compound of the present invention ora physiologically functional derivative thereof and one of the agentsmentioned herein below.

[0115] Examples of such further therapeutic agents include agents thatare effective for the modulation of immune system or associatedconditions such as AZT, 3TC, 8-substituted guanosine analogs,2′,3′-dideoxynucleosides, interleukin II, interferons such as(-interferon, tucaresol, levamisole, isoprinosine and cyclolignans.Certain compounds according to the present invention may be effectivefor enhancing the biological activity of certain agents according to thepresent invention by reducing the metabolism or inactivation of othercompounds and as such, are co-administered for this intended effect.

[0116] With respect to dosage, one of ordinary skill in the art willrecognize that a therapeutically effective amount will vary with theinfection or condition to be treated, its severity, the treatmentregimen to be employed, the pharmacokinetics of the agent used, as wellas the patient (animal or human) treated. Effective dosages may rangefrom 1 mg/kg of body weight, or less, to 25 mg/kg of body weight ormore. In general a therapeutically effective amount of the presentcompound in dosage form usually ranges from slightly less than about 1mg./kg. to about 25 mg./kg. of the patient, depending upon the compoundused, the condition or infection treated and the route ofadministration. This dosage range generally produces effective bloodlevel concentrations of active compound ranging from about 0.04 to about100 micrograms/cc of blood in the patient. It is contemplated, however,that an appropriate regimen will be developed by administering a smallamount, and then increasing the amount until either the side effectsbecome unduly adverse, or the intended effect is achieved.

[0117] Administration of the active compound may range from continuous(intravenous drip) to several oral administrations per day (for example,Q.I.D.) and may include oral, topical, parenteral, intramuscular,intravenous, sub-cutaneous, transdermal (which may include a penetrationenhancement agent), buccal and suppository administration, among otherroutes of administration.

[0118] To prepare the pharmaceutical compositions according to thepresent invention, a therapeutically effective amount of one or more ofthe compounds according to the present invention is preferablyintimately admixed with a pharmaceutically acceptable carrier accordingto conventional pharmaceutical compounding techniques to produce a dose.A carrier may take a wide variety of forms depending on the form ofpreparation desired for administration, e.g., oral or parenteral. Inpreparing pharmaceutical compositions in oral dosage form, any of theusual pharmaceutical media may be used. Thus, for liquid oralpreparations such as suspensions, elixirs and solutions, suitablecarriers and additives including water, glycols, oils, alcohols,flavouring agents, preservatives, colouring agents and the like may beused. For solid oral preparations such as powders, tablets, capsules,and for solid preparations such as suppositories, suitable carriers andadditives including starches, sugar carrier, such as dextrose, mannitol,lactose and related carriers, diluents, granulating agents, lubricants,binders, disintegrating agents and the like may be used. If desired, thetablets or capsules may be enteric-coated or sustained release bystandard techniques.

[0119] For parenteral formulations, the carrier will usually comprisesterile water or aqueous sodium chloride solution, though otheringredients including those which aid dispersion may be included. Ofcourse, where sterile water is to be used and maintained as sterile, thecompositions and carriers must also be sterilized. Injectablesuspensions may also be prepared, in which case appropriate liquidcarriers, suspending agents and the like may be employed.

[0120] Test Results

[0121] In vitro and in vivo tests on a compound of Formula I,L-Ribavirin, were performed, and the results are described below.

[0122] In a first series of experiments, peripheral blood mononuclearcells (PBMCs) were isolated from the buffy coat following Ficoll-Hypaquedensity gradient centrifugation of 60 ml blood from healthy donors.T-cells were then purified from the PBMCs using Lymphokwik lymphocyteisolation reagent specific for T-cells (LK-25T, One Lambda, Canoga ParkCalif.). An average yield of 40-60×10⁶ T-cells were then incubatedovernight at 37° C. in 20-30 ml RPMI-AP5 (RPMI-1640 medium (ICN, CostaMesa, Calif.) containing 20 mM HEPES buffer, pH 7.4, 5% autologousplasma, 1% L-glutamine, 1% penicillin/streptomycin and 0.05%2-mercaptoethanol) to remove any contaminating adherent cells. In allexperiments, T-cells were washed with RPMI-AP5 and then plated on96-well microtitre plates at a cell concentration of 1×10⁶ cells/ml.

[0123] The T-cells were activated by the addition of 500 ng ionomycinand 10 ng phorbol 12-myristate 13-acetate (PMA) (Calbiochem, La Jolla,Calif.) and incubated for 48-72 h at 37° C. PMA/ionomycin-activatedT-cells were treated with 0.5-50 μM of either Ribavirin (D-Ribavirin) orL-Ribavirin, or with 250-10000 U/ml of a control antiviral,interferon-alpha (Accurate, Westbury, N.Y.) immediately followingactivation and re-treated 24 h later. T-cells from each plate were usedfor immunofluorescence analysis and the supernatants used forextracellular cytokine measurements. Following activation, 900 μl cellsupernatant from each microplate was transferred to another microplatefor analysis of cell-derived cytokine production. The cells are thenused in immunofluorescence analyses for intracellular cytokine levelsand cytokine receptor expression.

[0124] Cell-derived human cytokine concentrations were determined incell supernatants from each microplate. Activation-induced changes ininterleukin-2 (IL-2) levels were determined using a commerciallyavailable ELISA kit (R & D systems Quantikine kit, Minneapolis, Minn.)or by bioassay using the IL-2-dependent cell line, CTLL-2 (ATCC,Rockville, Md. Activation-induced changes in interleukin-4 (IL-4), tumornecrosis factor (TNFα) interleukin-8 (IL-8) (R & D systems (Quantikinekit, Minneapolis, Minn.) and interferon-gamma (IFN-γ) (Endogen(Cambridge, Mass.) levels were determined using ELISA kits. All ELISAresults were expressed as pg/ml and the CTLL-2 bioassay as counts perminute representing the IL-2-dependent cellular incorporation of³H-thymidine (ICN, Costa Mesa, Calif.) by CTLL-2 cells.

[0125] Comparison of the effects of D-Ribavirin and L-Ribavirin(expressed as a percentage of activated control) on IL-2 TNFα, IFN-γ,IL-4 and IL-5 levels are presented in FIGS. 13 and 14.

[0126] In another set of experiments the effects of L-Ribavirin on theinflammatory ear response to dinitrofluorobenzene were determined. Theresults of those experiments are shown in FIG. 15.

[0127] Synthesis

[0128] The compounds according to the present invention may be producedaccording to synthetic methods which are individually readily known tothose of ordinary skill in the art. In general, compounds according tothe present invention are synthesized by condensing appropriatenucleoside base with the necessary sugar synthon to give the protectedL-nucleoside which on further manipulation and deprotection of the sugarhydroxyl protecting groups will ultimately give rise to nucleosideanalog having the desired ribofuranosyl moiety of the L-configuration.

[0129] During chemical synthesis of the various compositions accordingto the present invention, one of ordinary skill in the art will be ableto practice the present invention without undue experimentation. Inparticular, one of ordinary skill in the art will recognize the varioussteps that should be performed to introduce a particular substituent atthe desired position of the base or a substituent at the desiredposition on the sugar moiety. In addition, chemical steps which aretaken to protect fractional groups such as hydroxyl or amino groups,among others, as well as de-protected these same fractional groups, willbe recognized as appropriate within the circumstances of the syntheses.

[0130] The invention is further defined by reference to the followingexamples, which are intended to be illustrative and not limiting. Itwill be understood by one of ordinary skill in the art that theseexamples are in no way limiting and that variations of detail can bemade without departing from the spirit and scope of the presentinvention.

[0131] Compounds of The present invention may be prepared in accordancewith well known procedures in the art. Particularly useful are thefollowing synthetic schemes.

[0132] Scheme 1: Synthesis of ribofuranosyl (R1, R4, R5, R7 and R8, arehydrogens; R2, R3 and R6 are hydroxyl) nucleosides of formula (II):Triazole L-ribofuranosyl nucleosides were prepared by the acid catalyzedfusion procedure (Sato, T., et al, Nippon Kagaku Zasshi, 81, 1440,1960). Accordingly, the triazoles (1 were mixed with1,2,3,5-tetra-O-acetyl-L-ribose(2) and a catalytic amount ofbis(p-nitrophenyl)phosphate and heated at 160-165 C. for 30 min underreduced pressure to provide the required nucleosides which on furtherdeprotection furnished the triazole L-ribonucleosides (3) of formula(II).

[0133] Scheme 2: Synthesis of L-ribofuranosyl (R1, R4, R5, R7 and R8,are hydrogens; R2, R3 and R6 are hydroxyl) nucleosides of formula (III):Triazole, pyrazole and other 5-membered heterocyclic L-ribofuranosylnucleosides of the present invention were prepared by using Vorbruggenprocedure involves the treatment of the heterocycles (4) withchlorotrimethylsilane to provide the silyl intermediate which oncondensation with the protected ribose (5)in the presence of stannicchloride in an inert solvent affords the required nucleosides (6). Aftercondensation the products are deprotected by conventional methods knownto those skilled in the art, into compounds of the formula (III).

[0134] Most of compounds of the formula (III) can be prepared by usingthe above condensation procedure. The required1,2,3,5-tetra-O-acetyl-L-ribose and1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribose were prepared as shown inExample 2 and Example 13 respectively. The hetero monocyclic bases arecommercially available from Aldrich, Fluka, ICN, Acros, Alfa, Lancasterand TCI America or were prepared by following the reported procedurethat are available in the literature articles (Robins, R. K., et al,Nucleosides & Nucleotides, 13, 17-76, 1994). The preparation pyrrole,pyrazole and other type triazole L-nucleosides of formula (IV) wereachieved by following the procedures reported for the preparation of thecorresponding D-nucleosides in Chemistry of Nucleosides and Nucleotides,Edited by Leroy B. Townsend, New York, Plenum Press, 3, 1-105, 1994.Various imidazole L-nucleosides were prepared by following the reported(Shaw, G., in Chemistry of Nucleosides and Nucleotides, Edited by LeroyB. Townsend, New York, Plenum Press, 3, 263-420, 1994) methods toimidazole D-nucleosides.

[0135] Scheme 3: The compounds of formula (I) could be obtained byreacting the heterocycles (7) with L-ribose (5) by following theVorbruggen procedure (Niedballa, U., et al, J. Org. Chem., 39, 3654,1974) described above for the preparation of compounds of formula (III).

[0136] The C-nucleosides (where A is carbon in formulas I & III) ofL-configuration were prepared by exemplifying the procedure reported(Watanabe, K. A., in Chemistry of Nucleosides and Nucleotides, Edited byLeroy B. Townsend, New York, Plenum Press, 3, 421-535, 1994) for thepreparation their corresponding C-nucleosides of D-configuration.

[0137] Scheme 4: Preparation of L-arabinofuranosyl nucleosides (R₁, R₂,R₄, R₅ and R₈ are hydrogens; R₃, R₆ and R₇ are hydroxyl): The b-anomersof the arabinosyl L-nucleosides of formulae (I-III) may be prepared byreacting 2,3,5-tri-O-benzyl-L-arabinofuranosyl bromide (9; Baker, R., etal., J. Org. Chem., 26, 4605-4609, 1961) and the trimethylsilylderivative of the base to give the intermediate L-nucleoside (10).Removal of the blocking groups of 10 should afford the requiredb-L-arabinofuranosyl nucleosides. In the case of pyrroleb-L-arabinonucleosides the sodium salt glycosylation procedure(Revankar, G. R., et al, Nucleosides & Nucleotides, 6, 261-264, 1987)was followed.

[0138] Scheme 5: Preparation of L-xylofuranosyl nucleosides (R₁, R₃, R₄,R₅ and R₇ are hydrogens; R₂, R₆ and R are hydroxyl): The b-anomers ofthe xylofuranosyl L-nucleosides of formulae (I-III) may be prepared from1,2-di-O-acetyl-3,5-di-O-benzyl-L-xylofuranose (11; Gosselin, G., etal., J. Heterocyclic Chem., 30, 1229-1233, 1993) and the appropriatebase, by following the method analogous to that described in scheme 4.

[0139] Scheme 6: Preparation of L-2′-deoxyribofuranosyl nucleosides (R₁,R₂, R₄, R₅, R₇ and R₈ are hydrogens; R₃ and R₆ are hydroxyl): Theb-anomers of the 2′-deoxyribofuranosyl L-nucleosides of formulae (I-III)may be prepared by reacting3′,5′-Di-O-p-toluyl-2′-deoxyerythro-b-L-pentofuranosyl chloride (13)(Smejkal, J., et al, Collect. Czec. Chem. Commun. 29, 2809-2813, 1964)with the silyl derivative of the heterocycles in the presence ofBronsted acid to give exclusively the b-isomers (14) in good yield(Fujimori, S., et al, Nucleosides & Nucleotides, 11, 341-349, 1992;Aoyama, H., Bull. Chem. Soc., 60, 2073, 1987). The sameb-L-2′-deoxyribofuranosyl nucleosides were also prepared by the reactingthe chloro sugar (13) with sodium salt of the base (Kazimierczuk, Z., etal, J. Amer. Chem. Soc., 106, 6379-6382, 1984) in dry acetonitrile. Theintermediate (14) on treatment with methanolic ammonia provided therequired b-L-2′-deoxyerythro-pentofuranosyl nucleosides.

[0140] Scheme 7: Preparation of L-3′-deoxyribofuranosyl nucleosides (R₁,R₃, R₄, R₅, R₆, R₇ and R₈ are hydrogens; R₂ and R₆ are hydroxyl): Theb-anomers of the 3′-deoxyribofuranosyl L-nucleosides of formulae (I-III)may be prepared by reacting1,2-di-O-acetyl-5-O-benzoyl-3-deoxy-L-erythro-pentose (15) with thesilyl derivative of the heterocycles in the presence of Lewis acid togive the b-isomers (16), which on deblocking with methanolic ammoniashould give b-L-3′-deoxyerythro-pentofuranosyl nucleosides. The samecompounds could also be prepared by reacting the corresponding 1-chloroderivative of (15) with sodium salt of the heterocyclic base, as in thecase of 2′-deoxy L-nucleosides described in scheme 6.

[0141] Scheme 8: Preparation of L-2′,3′-dideoxyribofuranosyl nucleosides(R₁, R₂, R₃, R₄, R₅, R₇ and R₈ are hydrogens; R₆ is hydroxyl): Theb-anomers of the 2′,3′-dideoxyriboftiranosyl L-nucleosides of formulae(I-III) may be prepared by the treatment of their corresponding5′-O-triphenylmethyl-2′,3′-bis (methanesulfonate)-b-L-ribofuranosylnucleosides (17) with sodium hydrogentelluride (Clive, D. L., et al, J.Org. Chem., 61, 7426-7437, 1996) in CH₃CN at room temperature as shownbelow. Finally the trityl group will be removed from (18) under mildcondition to provide the 2′,3′-dideoxyribofuranosyl b-L-nucleosides.

[0142] Furthermore, substituted sugars such as1-bromo-2-deoxy-2-fluoro-3,6-O-benzoyl-L-arabinofuranose (Ma, T., et al,J. Med. Chem., 39 2835-2843, 1996) and other modified sugars ofL-configuration are known in U.S. Pat. No. 5,473,063; WO 96/13512; WO96/13498; WO 96/22778; WO 95/20595; U.S. Pat. Nos. 5,473,063; 5,567,688;WalczaK, K., et al, Monatsh. fur Chemie, 123, 349-354(1992); Wengel, J.,et al, J. Org. Chem., 56, 3591-3594(1991); Genu-Dellac, C., et al,Tetrahedron Letts., 32, 79-82(1991) and Czemecki, S., et al, Synthesis,783(1991). In addition, preparation of modified sugars and nucleosidesof D-configuration are described in U.S. Pat. No. 5,192,749; WO94/22890; Uteza, V., et al, Tetrahedron, 49, 8579-8588(1993); Thrane,H., et al, Tetrahedron, 51, 10389-10403(1995); Yoshimura, Y., et al,Nucleosides & Nucleotides, 14, 427-429 (1993; Lawrence, A. J., et al, J.Org. Chem., 61, 9213-9222(1996); Ichikawa, S., et al, J. Org. Chem., 62,1368-1375(1997); EP 0 457 326 A1; U.S. Pat. No. 3,910,885; WO 96/13498and Karpeisky, M,Y., et al, Nucleic Acids Res. Symposium Series, 9, 157(1981). By applying the synthetic procedures (schemes) that has beendescribed in these articles for the preparation of D-nucleosides, thecorresponding modified L-nucleosides could also be achieved.

[0143] Other compounds within the scope of the invention can besynthesized using the teachings of the schematics provided herein, aswell as the specific examples and other schemes set forth below. Inaddition to the teachings provided herein, the skilled artisan willreadily understand how to make compounds within the scope of the presentinvention by applying well known techniques such as those described inNucleic Acid Chemistry, Improved and New Synthetic Procedures, Methodsand Techniques, Edited by Leroy B. Townsend and R. Stuart Tipson, JohnWiley & Sons, New York (1978-1991); Chemistry of Nucleosides andNucleotides, Edited by Leroy B. Townsend, New York, Plenum Press(1988-1994) and Nucleosides and Nucleotides as Antitumor and AntiviralAgents, Edited by Chung K. Chu and David C. Baker, New York, PlenumPress (1993). Suitable methods for making substitution within the sugarmoiety of the presently claimed compounds are known to those skilled inthe art and are described in various publications including: U.S. Pat.Nos. 5,559,101; 5,192,749; 5,473,063; 5,565,438. Suitable methods formaking various heterocyclic compounds and substitution on them areprovided in Chemistry of Nucleosides and Nucleotides, Edited by Leroy B.Townsend, New York, Plenum Press, 2, 161-398 (1991) and Chemistry ofNucleosides and in Nucleotides, Edited by Leroy B. Townsend, New York,Plenum Press, 3, 1-535 (1994).

EXAMPLES

[0144] The invention can be further understood by referring to thefollowing examples below, wherein the compound numerals in boldcorrespond to like numbered numerals in FIGS. 1-12.

Examples 1 1-O-Methyl-2,3,5-Tri-O-acetyl-β-L-ribofuranose (19)

[0145] L-Ribose (15.0 g, 100 mmol) was dissolved in dry methanol (200mL) and cooled to 0° C. To this cold stirred solution H₂SO₄ (2 mL) wasadded slowly and the reaction mixture stirred at below 20° C. for 12 hunder argon atmosphere. Dry pyridine (75 mL) was added and evaporated todryness. Dry pyridine (100 mL) was added and evaporated under reducedpressure to an oily residue. This residue was dissolved in dry pyridine(150 mL) and treated with acetic anhydride (50 mL) at 0° C. under argonatmosphere. TEA (41 mL) was added, the reaction stirred at 0° C. for 1 hand at room temperature for 36 h, evaporated to dryness. The residue wasdissolved in water (200 mL), solid NaHCO₃ was added slowly to adjust thepH of the solution to 7. The aqueous mixture was extracted in CH₂Cl₂(250 mL), washed with water (150 mL) and brine (100 mL), dried andconcentrated. The oily residue was filtered on a bed of silica gel (200g), washed with CH₂Cl₂:EtOAc (8:2, 1000 mL). The filtrate was evaporatedand the oil was used as such for the next reaction.

Example 2 1,2,3,5-Tetra-O-acetyl-β-L-ribofuranose (2)

[0146] The syrup (19) (29.0 g, 100 mmol) from the above reaction wasco-evaporated with dry toluene (2×100 mL) and dried overnight undersolid NaOH at room temperature in vacuo. The dried syrup was dissolvedin glacial acetic acid (150 mL) and cooled to 0° C. under argonatmosphere. To this cold solution was added acetic anhydride (35 mL)followed by H₂SO₄ (10 mL) very slowly during 15 minute period. Thereaction mixture was stirred at room temperature overnight and pouredinto ice (200 g) with stirring. The mixture was extracted with CHCl₃(2×200 mL) and the organic extract was washed with water (200 mL), sat.NaHCO₃ (200 mL) and brine (150 mL), dried over anhydrous Na₂SO₄ andevaporated to dryness. The syrup 30 g (94%) that obtained was found tobe pure enough for glycosylation reactions.

Example 3A Methyl1-(2,3,5-Tri-O-acetyl-β-L-ribofuranosyl)-1,2,4-triazole-3-carboxylate(20)

[0147] A mixture of methyl 1,2,4-triazole-3-carboxylate (0.64 g, 5mmol), 1,2,3,5-tetra-O-acetyl-β-L-ribofuranose (2) (1.5 g, 4.72 mmol)and bis(p-nitrophenyl)-phosphate (20 mg) were placed in a pear shapedflask and placed in a preheated oil bath at (160-165° C.). The flask wasconnected to a water aspirator and kept at 160-165° C. (oil bathtemperature) under reduced pressure with stirring for 25 min. Thereaction mixture was removed, cooled and diluted with EtOAc (150 mL) andsat. NaHCO₃ (100 mL). The product was extracted in EtOAc. The organicextract was washed with water (100 mL) and brine (50 mL), dried andevaporated to dryness. The residue that obtained was purified by flashcolumn of silica gel using CHCl₃→EtOAc as the eluent. The pure fractionswere collected and evaporated to dryness to give 1.2 g (66%) of pureproduct: ¹H NMR (CDCl₃) δ2.10 (3s, 9H, 3 COCH₃), 3.98 (s, 3H, OCH₃),422(m 1H), 4.46 (m, 2H), 5.54 (t, 1H), 5.76 (m, 1H), 6.04 (d, 1H, C_(1′)H),and 8.38 (s,1H, C₃H). Anal Calc. for C₁₅H₁₉N₃O₉ (385.22): C, 46.75; H,4.97; N, 10.91. Found: C, 46.82; H, 4.57; N=10.71.

Example 3B 1-β-L-Ribofuranosyl-1,2,4-triazole-3-carboxamide (21)

[0148] The substrate (20) (1.1 g) was dissolved in CH₃OH/NH₃ at 0° C.and placed in a steel bomb. The bomb was closed and stirred at roomtemperature for 18 h. The steel bomb was cooled, opened and evaporatedto dryness. The residue was tried to crystallization with littleethanol. The product crystallized, but on filtration, the crystalsre-absorbed water and became a paste. The crystallization repeatedseveral times. Finally it crystallized from Methanol/Ethanol mixture.The colorless crystals was filtered, washed with methanol and dried invacuo. The filtrate was evaporated again which on standing gave furthercrystals. Total yield 0.5 g (72%); mp: 177-179° C.; [a]_(D)=+38.33 (c 3mg/mL H₂O); D form of Ribavirin [a]_(D)=−36.0 (c 3.0 mg/mL H₂O); ¹H NMR(Me₂SO-d₆) δ3.46 (m, 1H, C_(5′)H), 3.60 (m, 1H, C_(5′)H), 3.92 (q, 1H,C_(4′)H), 4.12 (q, 1H), 4.34 (q, 1H), 4.88 (t, 1H, C_(5′)OH), 5.20 (d,1H), 5.58 (d, 1H), 5.80 (d, 1H, C_(1′)H), 7.60 (bs, 1H, NH), 7.82 (bs,1H, NH), and 8.82 (s, 1H, C₃H). Anal. Calc. for C₈H₁₂N₄O₅ (244.20): C,39.34; H, 4.95; N, 22.94. Found: C, 39.23; H, 4.97; N, 22.91.

Example 4 2,3-O-Isopropylidene-L-ribose (22)

[0149] To a stirred suspension of L-ribose (30.0 g, 260 mmol) in dryacetone (200 mL) was added iodine (1.27 g, 10 mmol) at room temperatureunder argon atmosphere. The reaction mixture was stirred for 1 h (thesolution becomes homogeneous during this period) and quenched withsodium thiosulfate solution (1 M). The solution was evaporated todryness. The residue was dissolved in CH₂Cl₂ (250 mL), dried overanhydrous MgSO₄, filtered and the solid was washed with CH₂Cl₂ (150 mL).The combined filtrate was evaporated to dryness. The residue was placedon top of silica column (8×116 cm) packed in CHCl₃. The column waseluted with CHCl₃ (500 mL), CHCl₃:EtOAc (9:1, 1000 mL) and CHCl₃:EtOAc(7.3. 1500 mL). The pure product eluted in CHCl₃:EtOAc (7:3) wascollected and evaporated to give an oily residue 34.5 g (90%). The oilyproduct used as such for the next reaction. ¹H NMR (CDCl₃) δ1.30 and1.38 (2s, 6H, isopropylidene CH₃), 3.70 (m, 3H), 4.08 (m, 1H), 4.38 (m,1H), 4.55 (d, 1H), 4.81 (d, 1H) and 5.38 (m, 1H).

Example 5 1-Deoxy-1-hydrazinyl-2,3-O-isopropylidene-L-ribose (23)

[0150] A solution of 2,3-O-isopropylidene-L-ribose 22 (34.5 g, 182 mmol)in absolute methanol (200 mL) was treated with a solution of anhydroushydrazine (42.0 g, 1313 mmol) in absolute methanol (100 mL) drop-wiseover a period of 30 min and at room temperature under argon atmosphere.The nearly colorless solution was stirred at room temperature and underanhydrous condition for 18 h. The solution was evaporated in vacuo toafford a colorless syrup. The syrup was repeatedly co-evaporated withabsolute methanol (5×100 m). The resulting syrup was momentarily warmed(70° C.) under vacuum pump pressure (0.1 torr) and then kept at thispressure for drying for 12 h. The yield was 35.0 g (95%). This materialwas used as such without further purification for the next step.

Example 65-Amino-4-cyano-1-(2′,3′-O-isopropylidene-β-L-riboftiranosyl)pyrazole(24)

[0151] A solution of 1-deoxy-1-hydrazinyl-2,3-O-isopropylidene-L-ribose(23) (16.3 g, 79.90 mmol) in absolute ethanol (100 mL) was purged with asteady stream of argon for 30 min. A similarly purged solution of(ethoxymethylene)-malanonitrile (10.37 g, 85 mmol) in absolute ethanol(100 mL) was added drop-wise to the rapidly stirred solution at roomtemperature during a 1 h period. The solution was stirred under argonfor an additional 30 min and then heated at reflux for 12 h. The orangesolution was cooled to room temperature and evaporated in vacuo todryness. This material was dissolved in ethyl acetate (100 mL) and thentreated with silica gel (50 g). The mixture was evaporated to dryness invacuo and the powder which resulted was applied to the top of a silicagel (500 g) column (6×30 cm, dry packed). The column was eluted withgradient of CH₂Cl₂→EtOAc solvent. Fractions having the pure product werepooled together and evaporated to a foam: Yield 17 g (76%); ¹H NMR(CDCl₃) δ1.30 and 1.52 (2s, 6H, isopropylidene CH₃), 3.86 (m, 2H,C_(5′)H), 4.40 (m, 1H, C_(4′)H), 4.80 (bs, 2H, NH2), 5.00 (d,1H), 5.20(m, 1H), 5.80 (d, 1H, C_(1′)H) and 7.54 (bs, 1H, C₃H). Anal. Calc. forC₁₂H₁₆N₄O₄ (280.28): C, 51.43; H, 5.75; N, 19.99. Found: C, 51.20; H,5.63; N, 19.98.

Example 7 5-Amino-1-(β-L-ribofuranosyl)pyrazole-4-carbonitrile (25)

[0152] A solution of5-amino-1-(2′,3′-O-isopropylidene-p-β-ribofuranosyl)-pyrazole-4-carbonitrile(24) (4.6 g, 16.43 mmol) in 90% trifluoroacetic acid (30 mL) was stirredat room temperature for 4 h. The reaction mixture was evaporated todryness and the residue was co-evaporated with methanol (3×35 mL). Theresidue was used as such for further reactions.

Example 8 5-Amino-1-(β-L-ribofuranosyl)pyrazole-4-carboxamide (26)

[0153] To a solution of (25) (4.60 g) in ammonium hydroxide (35 mL) wasadded 30% hydrogen peroxide (2 mL). The mixture was stirred in apressure bottle at room temperature for 18 h, the pressure bottle wascooled, opened carefully and the volatile products were evaporated todryness. The residue thus obtained was co-evaporated with ethanol (3×20mL). The crude product on crystallization with ethanol/water gave purecompound 3.5 g (71%): ¹H NMR (DMSO-d₆) δ3.57 (m, 2H, C_(5′)CH₂), 3.86(q, 1H, C_(4′)H), 4.11 (q, 1H, C_(3′)H) 4.43 (q, 1, C_(2′)OH), 5.63 (d,1H, J=3.99 Hz, C_(1′)H), 6.51 (br s, 2H, NH₂), 6.71 and 7.26 (2br s, 2H,CONH₂) and 7.69 (s, 1H, C₃H). Anal. Calc. for C₉H₁₄N₄O₅ (258.23): C,41.86; H, 5.46; N, 21.69. Found: C, 41.57; H, 5.40; N, 21.61.

Example 95-Amino-1-(2′,3′-O-isopropylidene-β-L-ribofuranosyl)pyrazole-3,4-dicarbonitirile(27)

[0154] A solution of tetracyanoethylene (24.32 g, 190 mmol) in absoluteEtOH (100 mL) was added drop-wise with stirring to a solution of1-deoxy-1-hydrazinyl-2,3-2,3-O-isopropylidene-L-ribose (223.0 g, 113.0mmol) in EtOH (100 mL), over a period of 30 min at 0° C. The reactionmixture was stirred at ice-bath temperature for an additional 2 h andthen stirred at room temperature for 15 h. The brown solution wasfiltered and evaporated to dryness. The residue was dissolved in MeOH(50 mL), adsorbed onto silica gel (90 g), and placed on top of a silicagel column (10×25 cm) packed with CH₂Cl₂. The column was eluted withCH₂Cl₂/EtOAc (10:1, v/v); the homogeneous fractions were pooled andevaporated to dryness. The residual yellow foam was crystallized from aethanol on long standing at room temperature to yield 15 g (44%) of pure(27): mp ° C.; ¹H NMR (Me₂SO-d₆) δ1.31 and 1.48 (2s, 6H,isopropylidene-CH₃), 3.29 (m, 2H, C_(5′)CH₂), 4.13 (m, 1H, C_(4′)H),4.83 (m, 1H, C_(3′)H), 4.97 (t, 1H, C_(5′)OH), 5.24 (m, 1H, C_(2′)H),6.12 (s, 1H, C_(1′)H), 7.65 (s, 2H, NH₂). Anal. Calc. for C₁₃H₁₅N₅O₄(305.29): C,51.14; H, 4.95; N, 22.94. Found: C, 51.20; H, 5.04; N,22.61.

Example 10 5-Amino-1-β-L-ribofuranosylpyrazole-3,4-dicarbonitrile (28)

[0155] A suspension of5-amino-1-(2′,3′-O-isopropylidene-β-L-ribofuranosyl)-pyrazole-3,4-dicarbonitrile(4.6 g, 15.0 mmol) in 90% TFA/water (50 mL) was stirred at roomtemperature for 12 h. The solvent was evaporated and the residue wasco-evaporated with EtOH (3×50 mL). The light brown residue thus obtainedwas used as such for further reaction.

Example 11 5-Amino-1-β-L-ribofaranosylpyrazole-3,4-dicarboxamide (29)

[0156] The TFA salt of5-amino-1-β-L-ribofuranosylpyrazole-3,4-dicarbonitrile (28) (2.60 g,10.0 mmol) was dissolved in conc. NH₄OH (28%, 100 mL) and treated withH₂O₂ (30%, 15 mL). The reaction mixture was stirred at room temperaturein a pressure bottle for 12 h, and then evaporated to dryness. Theresidue was co-evaporated with MeOH (3×50 mL). The crude product wascrystallized from a mixture of EtOH/water to give 2.0 g (68%) of (29):mp×° C.; ¹H NMR (Me₂SO-d₆) δ3.60 (m, 2H, C_(5′)CH₂) 3.87 (m, 1H,C_(4′)H), 4.18 (m, 1H, C_(3′)H), 4.54 (m, 1H, C_(2′)H), 4.91 (t, 1H,C_(5′)OH), 5.03 and 5.38 (2d, 2H, C_(2′3′)OH), 569 (d, 1H, C_(1′)H, 6.99(br s, 3H, NH₂ and CONH(H)), 7.72 and 7.78 (2s, 2H, CONH₂), and 9.65 (d,1H, CON(H)H). Anal. Calc. for C₁₀H₁₅N₅O₆ (301.26): C, 39.87; H, 5.03; N,23.25. Found: C, 39.72; H, 5.40; N, 23.61

Example 12 Dimethyl 1,2,3-triazole-4,5-dicarboxylate (30)

[0157] To a stirred suspension of sodium azide (5.03 g, 77.39 mmol) inDMF (120 mL) was added dropwise at 0° C. over 30 min, a solution ofdimethyl acetylene-dicarboxylate (10.0 g, 70.36 mmol) in DMF (100 mL).After 30 min the solvent was removed in vacuo at 30° C. to leave a lightpurple-brown solid. The solid was washed twice with ether and taken upin water (100 mL). The aqueous solution was acidified with conc. HCl topH 2. The aqueous layer was first extracted with ether (100 mL) and thenwith chloroform (100 mL). The combined organic layers were evaporated togive a light red colored solid: 128-130° C. The solid was washed withhot hexane and crystallized from benzene: Yield 11.0 g (85%); ¹H NMR(CDCl₃) δ4.00 (s, 6H), 11.87 (br s, 1H, NH).

Example 13 1-O-Acetyl-2,3,5-tri-O-benzoyl-β-L-riboftiranose (5)

[0158] To a solution of L-ribose (25.0 g, 166.66 mmol) in MeOH (300 mL),was added 25 mL of sat. methanolic hydrogen chloride and stirred at roomtemperature for 6 h. The reaction was complete after 6 h as indicated byTLC using CH₂Cl₂/MeOH 9:1. After completion of the reaction, drypyridine (30 mL) was added and the solvents were evaporated. To theresidue another 30 mL of pyridine was added and evaporated to dryness.The residue was dissolved in dry pyridine (200 mL) and CH₂Cl₂ (150 mL)then cooled to 0° C. Benzoyl chloride (96.26 mL, 830.12 mmol) was addeddrop-wise and stirred at room temperature overnight. TLC usinghexane/ethyl acetate (7:3), indicated completion of the reaction. Thesolvents were evaporated and the residue dissolved in CHCl₃ (300 mL),and washed with H₂O (200 mL) and sat. NaHCO₃ (200 mL), and dried overanhydrous Na₂SO₄. After evaporating the CHCl₃, the residue wasco-evaporated with toluene to give an oily residue. The residue wasdissolved in AcOH (200 mL), acetic anhydride (85.0 mL; 770.9 mmol) andsulfuric acid (4.46 mL; 83.29 mmol). The reaction mixture was stirred atroom temperature overnight, after which time TLC (hexane/ethyl acetate7:3) indicated completion of the reaction. The solvents were evaporatedin vacuo and the residue that obtained was co-evaporated with toluene.The brown residue was triturated with EtOH to give light brown crystals.Filtration of the solid and recrystallization from EtOH gave1-O-acetyl-2,3,5-tri-O-benzoyl-L(+)-glucofuranose 40.5 g (48.0%) aswhite crystals: mp 125-125° C.; ¹H NMR (CDCl₃) δ4.49 (m, 1H, C_(5′)H),4.77 (m, 2H, C_(4′)H and C_(5′)H), 5.80 (d, 1H), 5.93 (m, 1H, C_(2′)H),6.43 (d, 1H, C_(1′)H, J_(1,2)=1.5 Hz) and 7.30-8.09 (m, 15H, PhH).

Example 14 Dimethyl2-(2′,3′,5′-tri-O-benzoyl-β-L-ribofuranosyl)-1,2,3-triazole-4,5-dicarboxylate(31)

[0159] A mixture of dry dimethyl 1,2,3-triazole-4,5-dicarboxylate (3.70g, 20.0 mmol), hexamethyldisilazane (HMDS, 60 mL), and (NH₄)₂SO₄ (0.1 g)was heated under reflux (oil-bath temperature 140° C.) for 12 h with theexclusion of moisture. Excess HMDS was removed by distillation in vacuoto provide the trimethylsilyl derivative, which was dissolved inanhydrous CH₃CN (100 mL).

[0160] To the above clear solution was added 1-O-acetyl 2,3,5tri-O-benzoyl-L-ribofuranose (10.12 g, 20 mmol) and the mixture wasstirred for 10 min. To this stirred solution was added trimethylsilyltrifluoromethanesulfonate (4.6 mL, 26.0 mmol) and the stirring wascontinued for 12 h at ambient temperature. The reaction mixture wasevaporated ant the residue was dissolved in CH₂Cl₂ (500 mL). The organiclayer was washed successively with aqueous sat. NaHCO₃ solution (3×100mL), sat. NaCl solution (×100 mL), and water (×50 mL) and dried overanhydrous Na₂SO₄. The solvent was evaporated furnish 12.0 g (95%) of 31:¹H NMR (Me₂SO-d₆) δ3.88 (s, 6H, 2 OCH₃), 4.65 (m, 2H, C_(5′)H), 5.01 (m,1H, C_(4′)H), 6.10 (m, 1H, C_(3′)H), 3.32 (m, 1H, C₂′H), δ6.88 (d, 1H,C_(1′)H, J_(1,2)=2.75 Hz) and 7.45-7.95 (m, 15H, PhH).

Example 15 2-β-L-Ribofuranosyl-1,2,3-triazole-4,5-dicarboxamide (32)

[0161] Compound 31 (6.0 g, 9.5 mmol) was dissolved in MeOH/NH₃ (dry MeOHsat. with anhydrous NH₃ at 0° C., 60 mL) were placed in a steel reactionvessel. The vessel was heated at 95° C. for 16 h. The reaction vesselwas cooled, opened carefully and the NH₃ was allowed to evaporate atroom temperature. The MeOH was evaporated to dryness and the residue wastriturated with hot toluene (3×50 mL) and filtered. The brown residuewas crystallized from aqueous EtOh (95) to furnish 2.40 g (89%) of 32:mp 210-212° C.; ¹H NMR (Me₂SO-d₆) δ3.45-3.59 (m, 2H, C_(5′)H), 3.98 (m,1H, C_(4′)H), 4.25 (m, 1H, C_(3′)H), 4.54 (m, 1H, C_(2′)H), 4.78 (t, 1H,C_(5′)OH, D₂O exchangeable), 5.27 and 5.67 (2d, 2H, C_(2′3′)OH, D₂Oexchangeable), 5.89 (d, 1H, J_(1′,2′)=3.85 Hz, C_(1′)H), 8.05 and 9.05(2br s, 4H, 2 CONH₂). Anal. Calc. for C₉H₁₃N₅O₆ (287.23): C, 37.63; H,4.56; N, 24.38. Found: C, 37.52; H, 4.19; N, 24.59.

Example 161-(2′,3′,5′-Tri-O-benzoyl-β-L-riboftiranosyl)pyridine-4-one-3-carboxamide(33)

[0162] To a mixture of hexamethyldisilazane (50 mL, 239.77 mmol) andchlorotrimethylsilane (1.0 mL, 21.43 mmol) was addedpyridine-4-one-3-carboxamide (1.38 g, 10.0 mmol) (Prepared by theprocedure reported: W. C. J. Ross, J. Chem. Soc., C, 1816, (1966); W.Herz and D. R. K. Murty, J. Org. Chem., 26, 122, 1961). The mixture wasrefluxed with stirring for 2 h and then evaporated to dryness undervacuum and further dried under high vacuum for 2 h at 60° C. The drygummy residue was suspended in freshly distilled 1.2-dichlorethane (50mL) and to this suspension was added1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (5.06 g, 10.0 mmol) andfreshly distilled SnCl₄ (1.0 mL, 8.52 mmol). The reaction mixture wasrefluxed for 1.5 h, cooled and diluted with CH₂Cl₂ (100 ml) and sat.aqueous NaHCO₃ (25 ml). The Mixture was filtered through celite and thebed was washed with Ch₂Cl₂ (20 mL). The mixture was filtered washed withwater until the washings are neutral, dried over anhydrous sodiumsulfate. The organic extract was evaporated to dryness to give a gummyresidue. The residue was purified by flash chromatography over silicagel using CH₂Cl₂→EtOAc as the eluent. Pure fractions were pooled andconcentrated to provide 0.50 g (9%) of 33 as white foam: ¹H NMR (CDCl₃):δ4.94 (m, 3H, C_(4′)H and C_(5′)H), 6.12 (m, 1H), 6.20 (m, 1H), 6.32 (d,1H) and 7.20-8.30 (m, 20H).

Example 17 1-δ-L-ribofuranosylpyridine-4-one-3-carboxamide (34)

[0163] Compound 33 (0.5 g, 0.86 mmol) was dissolved in dry methanolicammonia (50 mL) and stirred for 15 h in a bomb at room temperature. Thesolution is then concentrated to a small volume and cooled overnight at4° C. The crystalline product formed was filtered off, washed with coldmethanol. The solid was recyrstallized from absolute ethanol to give0.23 g (87%) of pure product: mp 209-211° C.; ¹H NMR (Me₂SO-d₆) δ3.60(m, 2H, C_(5′)H), 3.93 (m, 1H, C_(4′)H), 4.09 (m, 1H, C_(3′)H), 4.34 (m,1H, C_(2′)H), 5.11 (m, 1H, C_(5′)OH, D₂O exchangeable), 5.22 and 5.47(2m, 2H, C_(2′3,′)OH, D₂O exchangeable), 5.84 (d, 1H, J_(1′,2′)=6.3 Hz,C_(1′)H), 7.21 (m, 2H, PhH), 7.64 (m, 2H, PhH and CONH₂) and 8.44 (s,1H, CONH₂). Anal. Calc. for C₁₁H₁₄N₂O₆ (270.24): C, 48.89; H, 5.22;N,10.37. Found: C, 48.89; H, 5.42; N,10.51.

Example 18 2,3,5-Tri-O-benzoyl-β-ribofuranosyl Azide (35)

[0164] Dry hydrogen chloride was passed through a suspension of finelypowdered and dried 1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribose (20.0 g,39.52 mmol) in ether (300 mL.) at 0° C. until a clear solution obtained(2-3 h). The mixture was then set aside at 0° C. overnight. The solventwas removed and the residual gum evaporated successively with drybenzene (2×25 mL.) and toluene (25 mL.). The residue was dissolved inmethyl cyanide (250 mL). To this was added sodium azide (20.0 g, 307.6mmol) and the reaction mixture was refluxed under argon atmosphere for 2h. After the completion of the reaction, as determined by TLChexane/ethyl acetate (7:3), the solution was filtered and evaporated togive an oily product (14.6 g) in quantitative yield. The product gave awhite foam under high vacuum drying. The dried material was used as suchfor further reaction. ¹H NMR (CDCl₃) δ4.54 (m, 1H), 4.76 (m, 2H),5.57-5.58 (dd, 1H), 5.68 (d, 1H, J=1.65 Hz), 5.84-5.86 (m, 1H) and7.34-8.12 (m, 15H, PhH).

Example 195-Amino-1-(2′,3′,5′-tri-O-acetyl-β-L-ribofuranosyl)triazole-4-carboxamide(36)

[0165] N,N-Dimethylformamide (60 mL) was added to a cold (0° C.)solution of potassium hydrocide (1.72 g, 30.7 mmol) in water (10 mL) andthe solution stirred at this temperature for 10 min. Cyanoacetamide(2.58 g, 30.68 mmol) was added to this solution and the mixture was thenstirred at 0° C. until all the solid material had dissolved. To thissolution was added 2,3,5-tri-O-benzoyl-b-L-ribofuranosyl azide (10.0 g,20.5 mmol) in one portion, and the reaction was stirred at −5° C. for 14h. The amber solution was evaporated in vacuo (water bath 50° C.) toafford an orange semisolid, which was successively co-evaporated withabsolute ethanol (2×50 mL) and toluene (3×50 mL) in vacuo to afford athick orange gum. The gum was dissolved in anhydrous methanol (150 mL),sodium methoxide (1 N, 25 mL) was added and the solution was stirred atroom temperature under anhydrous conditions for 6 h. The amber solutionwas treated with Dowex 50×H⁺ ion-exchange resin (ca. 35 mL wet resin) toadjust the pH to 6. The solution was filtered, the resin bed was washedwith an additional methanol (50 mL) and the combined filtrates wereevaprated to dryness in vacuo (water bath 80° C.) to yield an orangegum. The gum was repeatedly triturated with ethyl acetate (6×50 mL), andeach portion was in turn decanted until the gum solidified to a tanamorphous solid. The off-white crude product 2.5 g (32%) waschromatographically pure. After several crystallization the productcontained impurities it is converted to the acetate form as describedbelow.

[0166] The above crude material (0.4 g, 1.54 mmol) was dissolved in drypyridine (10 mL). The solution was cooled to 0° C. under argonatmosphere and treated with acetic anhydride (0.95 g, 9.26 mmol). Thereaction mixture was stirred at room temperature overnight and thequenched with methanol (1.0 mL). The solvent was removed and the residuedissolved in CH₂Cl₂ (100 mL). The organic layer was washed with sat.NaHCHO₃ (100 mL) and brine (50 mL), dried and evaporated to dryness. Thecrude product was purified by flash chromatography over silica gel usingEtOAc as the eluent: Yield 0.52 g (88%); ¹H NMR (CDCl₃) δ2.12 (3s, 9H, 3COCH₃), 4.32-4.52 (m, 3H), 5.64 (m, 1H, C_(3′)H), 5.85 (m, 1H, C_(2′)H),6.00 (br s, 2H, NH₂), 6.32 (d, 1H C_(1′)H) and 8.73 (br s, 2H, CONH₂).

Example 20 5-Amino-1-β-L-(+)-ribofuranosyltriazole-4-carboxamide (37)

[0167] Compound 36 (0.5 g, 1.29 mmol) was dissolved in methanolicammonia (50 mL, sat. at 0° C.). The reaction mixture was stirred at roomtemperature for 16 h and evaporated to dryness. The residue wastriturated thrice with EtOAc and the solid was crystallized from minimumamount of dry EtOH to yield colorless solid: mp 159-161° C.; ¹H NMR(Me₂SO-d₆) δ3.40-3.52 (m, 2H, C_(5′)H), 3.93 (m, 1H, C_(4′)H), 4.19 (m,1H, C_(3′)H), 4.46 (m, 1H, C_(2′)H) 4.74, 5.22, 5.62 (m, 3H, 3 OH, D₂Oexchangeable), 5.84 (d, 1H, J=3.90 Hz, C_(1′)H), 7.95 (br s, 2H) and9.02 (br s, 2H). Anal. Calc. for C₈H₁₃N₅O₅ (259.22): C, 37.07; H, 5.05;N, 27.02. Found: C, 37.36; H, 5.14; N, 27.01.

Example 215-O-Acetyl-1-(2′,3′,5′-tri-O-acetyl-β-L-ribofuranosyl)triazole-4-carboxamide(3)

[0168] N,N-Dimethylformamide (40 mL) was added to a cold (0° C.)solution of potassium 10 min. Ethyl malonamate (2.73 g, 20.82 mmol) wasadded to this solution, and the mixture was then stirred at 0° C. untilall of the solid material had dissolved. To this solution was added2,3,5-tri-O-benzoyl-β-L-ribofuranosyl azide (6.76 g, 13.88 mmol) in oneportion, and the reaction was stirred at −5° C. for 14 h. The ambersolution is evaporated in vacuo (water bath 80° C. to afford an orangesemisolid, which was successively co-evaporated with absolute ethanol(2×50 mL) and toluene (3×50 mL) in vacuo to afford a thick orange gum.The gum was dissolved in anhydrous methanol (150 mL), sodium methoxide(0.5 N, 10 mL) was added and the solution was stirred at roomtemperature under anhydrous condition for 6 h. The amber solution wastreated with Dowex 50×H⁺ ion-exchange resin (ca. 35 mL wet resin) toadjust the pH to 6. The solution was filtered, the resin bed was washedwith an additional 50 mL of methanol, and the combined filtrates wereevaporated to dryness in vacuo (water bath 80° C.) to yield an orangegum. The gum was repeatedly triturated with ethyl acetate (6×50 mL), andeach portion was in turn decanted until the gum solidified to a tanamorphous solid. The solid was suspended in anhydrous pyridine (30 mL)and acetic anhydride (7.8 mL, 83.28 mmol), stirred under anhydrousconditions at room temperature for 18 h. The reaction mixture wasfiltered through a shallow bed of packed Celite. The Celite bed waswashed with fresh pyridine (50 mL) and the combined filtrates wereevaporated to dryness in vacuo to yield a brown gum. The gum wasdissolved in CH₂Cl₂ (150 mL). The organic layer was washed with sat.NaHCO₃ (100 mL) and brine (50 mL), dried and evaporated to dryness. Thecrude product was purified by flash chromatography over silica gel usingCH₂Cl₂→EtOAc as the eluent. Pure fractions were collected and evaporatedto provide 1.5 g (42%) of pure product 38. ¹H NMR (CDCl₃) δ2.14 (3s, 9H,3 COCH₃), 2.60 (s, 3H, COCH₃), 4.15-4.58 (m, 3H, C_(4′)H and C_(5′)H),5.62 (m, 1H, C_(3′)H), 5.82 (m, 1H, C_(2′)H), 6.28 (d, 1H, C_(1′)H) and10.63 (br s, 2H, CONH₂).

Example 22 5-Hydroxy-1-β-L(+)-ribofuranosyltriazole-4-carboxamide (39)

[0169] Compound 38 (1.5 g, 3.50 mmol) was dissolved in meth; methanolicammonia (50 mL, saturated at ° C.). The reaction mixture was stirred atroom temperature for 16 h and evaporated to dryness. The residue wastriturated thrice with EtOAc and the solid was crystallized form minimumamount of dry EtOH to yield 0.70 g (77%) of 39: mp 162-164° C.; ¹H NMR(Me₂SO-d₆) δ3.40-3.50 (m, 2H, C_(5′)H), 3.84 (m, 1H, C_(4′)H), 4.17 (m,1H, C_(3′)H), 4.32 (, 1H, C_(2′)H), 4.90 (t, 1H, C_(5′)OH), 5.20, 5.58(2d, 2H, 2 OH, D₂O exchangeable), 5.76 (d, 1H, J=3.90 Hz, C_(1′)H), 7.58and 7.80 (2br s, 2H, CONH₂) and 8.82 (s, 1H, C₅OH). Anal. Calc. forC₈H₁₂N₄O₆ (260.21): C, 36.92; H, 4.65; N, 21.53. Found: C, 36.90; H,4.79; N, 21.43.

Example 23 1-(2′,3′,5′-Tri-O-benzoyl-β-L-ribofuranosyl)-6-methyluracil(40)

[0170] A mixture of 6-methyluracil (2.52 g, 20.0 mmol),hexamethyldisilazine (50 mL) and ammonium sulfate (100 mg ) wererefluxed at 135° C. for 6 h. The solvent was removed in vacuo and theresidue that obtained was co-evaporated twice with dry toluene (2×50 mL)to remove last traces of hexamethyldisilazine. The solid thus obtainedwas dried under vacuum for 6 h. A solution of the2,4-bis(trimethylsilyloxy)-6-methylpyrimidine (20.0 mmol) in dryacetonitrile (100 mL) was added1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (10.12 g, 20 mmol) andtrimethylsilyltriflate (5.78 g, 26.0 mmol. The reaction mixture wasstirred under argon at room temperature for 16 h. The reaction mixturewas concentrated in vacuo and the residue was dissolved indichloromethane (200 mL). The organic layer was washed with sat. sodiumbicarbonate (200 mL) and brine (100 mL), dried over sodium sulfate andconcentrated to yield a white foam. Further separation of the crudeproduct by silica gel flash column chromatography using the CH₂Cl₂→EtOAcas the eluent gave two products. Yield of the 2^(nd) fraction 4.50 g(42%). ¹H NMR (CDCl₃) δ2.28 (s, 3H, CH₃), 4.65-4.81 (m, 3H, C_(4′)H andC_(5′)H), 5.60 (m, 1H, C_(3′)H), 5.72 (s, 1H), 6.11 (m, 1H), 7.24-8.06(m, 16H, PhH) and 9.40 (br s, 1H, NH). The first fraction (4.20 g) didnot correspond to the desired compound according to ¹H NMR.

Example 24 1-β-L-Ribofuranosyl-6-methyluracil (41)

[0171] A solution of 40 (4.50 g, 7.86 mmol) was dissolved in sat.methanolic ammonia (60 mL). The reaction mixture was heated at 100° C.for 17 h in a steel bomb. The reaction vessel was cooled to roomtemperature and concentrated to yield an oil. The reside was furtherpurified by silica gel flash column chromatography using dichloromethaneand methanol (9:1) as the eluent. Pure fractions were collected andevaporated to give a white solid. This was further recyrstallized from2-propanol to afford 1.98 g (94%) of pure 41: mp 175-177° C.; ¹H NMR(Me₂SO-d₆) δ2.24 (s, 3H, CH₃), 3.42-3.57 (m, 2H, C_(5′)H), 3.68 (m, 1H,C_(4′)H), 4.0 (m, 1H, C_(3′)H), 4.53 (m, 1H, C_(2′)H), 4.68, 4.94, 5.22(m, 3H, 3 OH, D₂O exchangeable), 5.43 (d, 1H, C_(1′)H, J_(1′,2′)=3.85Hz), 5.56 (s, 1H, C₅H) and 11.25 (s, 1H, NH). Anal. Calc. for C₁₀H₁₄N₂O₆(258.23): C, 46.51; H, 5.46; N, 10.85. Found: C, 46.66; H, 5.26; N,10.66.

Example 25 1-(2′,3′,5′-Tri-O-benzoyl-β-L-ribofuranosyl)-5-azacytidine(42)

[0172] 5-Azacytosine (1.12 g, 10.0 mmol) was suspended in a mixture ofhexamethyldisilazine (50 mL) and of ammonium sulfate(100 mg). Thereaction mixture was refluxed at 135° C. for 6 h. Later, the solventswere removed in vacuo and the residue thus obtained was co-evaporatedtwice from dry toluene (2×50 mL) to remove last traces ofhexamethyldisilazine. The solid thus obtained was dried under vacuo for6 h. To a solution of 2,4-N, bis(trimethylsilyl)-5-azacytidine (10.0mmol) in dry 1,2-dichlorethane (150 mL) was added1-O-acetyl-2,3,5-tri-O-benzoyl-b-L-ribofuranose (5.06 g, 10 mmol) andtin tetrachloride (1.68 mL, 14.16 mmol) at 10° C. The checked by TLCusing hexane and ethyl acetate (7:3). TLC indicated that no startingmaterial remained. The reaction mixture was diluted with dichloromethane(250 mL). The organic layer is washed with sat. sodium bicarbonate (200mL) and brine (100 mL), dried over sodium sulfate and concentrated to aresidue. The residue was dissolved in toluene and filtered throughcelite to remove unreacted 5-azacytosine. The filtrate was evaporated todryness and the residue (5.20 g) was dissolved in ethanol and filteredagain through celite. The titled compound was crystallized from thefiltrate as needles 4.45 g (81%): mp 186-187° C.; ¹H NMR (CDCl₃)δ4.62-4.66 (m, 3H, C_(4′)H and C_(5′)H), 6.01 (m, 3H, C_(1′)H, C_(2′)Hand C_(3′)H), 7.26-8.06 (m, 17H, NH₂ and PhH) and 8.48 (s, 1H, C₆H).

Example 26 4-Amino-1-β-L-ribofuranosyltriazin-2(1H)-one (5-Azacytidine,43)

[0173] Compound 42 (4.0 g, 7.19 mmol) was dissolved in absolute methanol(60 mL), heated to the boiling and treated with 0.5 M sodium methoxide(20 mL, 10.0 mmol). The starting material rapidly dissolved and thesolution immediately deposited the product. The mixture was kept for 4 hat room temperature and overnight in a refrigerator. The crystals arecollected, washed with ice-cold methanol (10 mL) and dried under reducedpressure at room temperature. Yield 1.50 g (86%). Analytical sample wasobtained by re-crystallization from water-acetone (1:1): mp 222-222° C.;¹H NMR (D₂O) δ3.78-3.97 (m, 2H, C_(5′)H), 4.13 (m, 1H, C_(4′)H), 4.20(m, 1H, C_(3′)H), 4.33 (m, 1H, C_(2′)H), 6.31 (d, 1H, C_(1′)H,J_(1′,2′)=2.5 Hz) and 8.24 (s, 1H, C₆H). Anal. Calc. for C₈H₁₂N₄O₅(244.20): C, 39.35; H, 4.95; N, 22.94. Found C, 34.09; H, 4.28; N,22.98.

Example 27 1-(2′,3′,5′-Tri-O-benzoyl-β-L-ribofuranosyl)-6-azauridine(44)

[0174] 6-Azauracil (1.36 g, 12.0 mmol), was suspended in a mixture ofhexamethyldisilazine (50 mL) and ammonium sulfate (50 mg). The reactionmixture was refluxed at 135° C. for 6 h. Later, the solvents wereremoved in vacuo and the residue that obtained was co-evaporated twicefrom dry toluene (2×50 mL) to remove last traces ofhexamethyldisilazine. The solid was dried in vacuo for 6 h and used inthe next step of synthesis without further characterization. To a wasadded 1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (5.06 g, 10 mmol)and tin tetrachloride (1.68 mL, 14.16 mmol) at 10° C. The reactionmixture was stirred under the atmosphere of argon at room temperaturefor 6 h. The reaction was checked by TLC using hexane and ethyl acetate(7:3). TLC indicated no starting material remained. The reaction mixturewas diluted with dichloromethane (250 mL). The organic layer is washedwith cold sat. sodium bicarbonate (150 mL) and brine (100 mL), driedover sodium sulfate and concentrated to a white foam. The residue wasdissolved in dichloromethane (100 mL) and filtered through celite toremove unreacted 6-azauracil. The filtrate was evaporated to a residue(4.50 g), dissolved in minimum amount of ehanol and filtered againthrough celite. The title compound was crystallized from the filtrate asneedles to give 4.50 g (79%) of pure 44: mp 193-195° C.; ¹H NMR(Me₂SO-d₆) δ4.47-4.67 (m, 3H, C_(5′)H), 4.71 (m, 1H, C_(4′)H), 5.85 (m,1H, C_(3′)H), 5.93 (m, 1H, C_(2′)H), 6.38 (d, 1H, J_(1′,2′)=2.56 Hz,C_(1′)H), 7.26-8.06 (m, 16H, C₅H and 12.32 (s, 1H, NH).

Example 28 1-β-L-Ribofuranosyl-6-azauracil (6-Azauridine 45)

[0175] Compound 44 (4.5 g, 7.95 mmol) was dissolved in absolutemethanolic ammonia (60 mL) and placed in a steel bomb. The was heated at100° C. for 16 h. Later, the reaction vessel was cooled to roomtemperature and the solvent was removed under vacuum. The residue thatobtained was triturated with hot toluene (2×50 mL). The residue wasdissolved in 95% ethanol and left at room temperature. The white solidcrystals that were obtained was collected by filtration and dried invacuo. Yield 1.75 g (89%): mp 151-153° C.; ¹H NMR (Me₂SO-d₆) δ3.30-3.47(m, 2H, C₅,H), 3.73 (m, 1H, C_(4′)H), 3.92 (m, 1H, C_(3′)H), 4.17 (m,1H, C_(2′)H), 4.62, 4.98, 5.22 (3br s, 1H, 3 OH, D₂O exchangeable), 5.82(d, 1H, C_(1′)H, J_(1′,2′)=3.85 Hz), 7.48 (s, 1H, C₅H) and 11.20 (br s,1H, NH). Anal. Calc. for C₈H₁₁N₃O₆ (245.19): C, 29.19; H, 4.52; N,17.14. Found: C, 38.81; H, 4.58; N, 17.04.

Example 29 Diethyl imidazole-4,5-dicarboxylate (46)

[0176] Imidazole-4,5-dicarboxylic acid (7.55 g, 50.0 mmol) is dissolvedin absolute ethyl alcohol (120 mL). The solution was cooled in an icebath to 0° C. and bubbled dry HCl gas for 1 h. Later, the reactionmixture was refluxed at 80° C. for 7 h during which time all thestarting material was consumed. The solvent was removed and the residuethat obtained was dissolved in dichloromethane (200 mL) and the organiclayer was neutralized with triethylamine. The organic layer was washedwith cold water (100 mL) and brine (50 mL), dried over anhydrous sodiumsulfate and concentrated in vacuo to give 5.50 g (52%) of white solid:mp 175-177° C.; ¹H NMR (CDCl₃) δ1.40 (t, 3H), 4.41 (m, 2H), 7.84 (1H,C₂H) and 11.55 (br s, 1H, NH).

Example 30 Diethyl1-(2′,3′,5′-tri-O-benzoyl-β-L-ribofuranosyl)imidazole-4,5-dicarboxylate(47)

[0177] A mixture of diethyl imidazole-4,5-dicarboxylate (2.65 g, 12.50mmol) and ammonium sulfate (50 mg) was heated at reflux at 135° C. for 6h with hexamethyldisilazine (50 mL). The reaction mixture was evaporatedto dryness and the residue was co-evaporated twice with dry toluene(2×50 mL) to remove last traces of hexamethyldisilazine. The solid thatobtained was dried in vacuo for 6 h and used for the next step withoutfurther characterization. To a solution of the above residue (12.5 mmol)in 1,2-dichlorethane (60 mL) was added1-O-acetyl-2,3,5-tri-O-benzoyl-L-ribofuranose (5.06 g, 10 mmol) and tintetrachloride (1.68 mL, 14.16 mmol) at 10° C. The reaction mixture wasstirred under the atmosphere of argon at room temperature for 6 h. Thereaction was checked by TLC using hexane and ethyl acetate (7:3). TLCindicated no starting material remained. The reaction mixture wasdiluted with dichloromethane (200 mL). The organic layer was washed withcold sat. sodium bicarbonate (200 mL) and brine (100 mL), dried oversodium sulfate and concentrated to yield a white foam. The residue wasdissolved in dichloromethane (100 mL) and filtered through celite toremove tin salts. After evaporation in vacuo the residue (4.70 g) wasdissolved in ethanol and filtered again through celite. The titledcompound 47 was crystallized form the filtrate as needles. Yield 4.70 g(72%): mp 134-136° C.; ¹H NMR (CDCl₄) δ1.28 (t, 3H, CH₃), 1.37 (t, 3H,CH₃), 4.28-4.40 (m, 4H, 2CH₂), 4.65-4.88 (m, 3H, C_(4′)H and C₅,H), 5.85(m, 2H, C_(2′)H and C_(3′)H), 6.68 (d, 1H, C_(1′)H, J_(1′,2′)=3.90 Hz)and 7.26-8.08 (m, 16H, C₂H and PhH).

Example 31 1-β-L-Ribofuranosylimidazole-4,5-dicarboxamide (48)

[0178] Compound 47 (4.0 g, 6.09 mmol) was dissolved in of absolutemethanolic ammonia (60 mL) and heated at 100° C. for 16 h in a steelbomb. Later, the reaction mixture was cooled to room temperature. Theproduct crystallized out from methanol. The precipitated product wasremoved by filtration and the filtrate was concentrated further to yieldthe second crop of the product. The combined product was recrystallizedonce again from methanol to furnish 1.68 g (100%) of white solid: mp224-226° C.; ¹H NMR (Me₂SO-d₆) δ3.53-3.75 (m, 2H, C_(5′)H), 3.84 (m, 1H,C_(4′)H), 3.96 (m, 2H, C_(2′)H and C_(3′)H), 4.97, 5.16, 5.36 (3br s,3H, 3 OH, D₂O exchangeable), 6.49 (d, 1H, C_(1′)H, J_(1′,2′)=2.1 Hz),7.60 (s, 1H, CONH₂), 7.88 (s, 1H, CONH₂), 7.99 (s, 1H, CONH₂), 8.48 (s,1H, C₂H) and 10.59 (s, 1H, CONH₂). Anal. Calc. for C₁₀H₁₄N₄O₆ (286.24):C, 41.96; H, 4.93; N, 19.57. Found: C, 41.89; H, 5.05; N, 19.41.

Example 32 Ethyl1-(2′,3′,5′-tri-O-benzoyl-β-L-ribofuranosyl)-3-hydroxy-1,2-pyrazole-4-carboxylate

[0179] A mixture of ethyl 3-Hydroxy-1,2-pyrazole-4-carboxylate (1.95 g,12.50 mmol) and ammonium sulfate (50 mg) in hexamethyldisilazine (50 mL)was heated at reflux for 6 h. The reaction mixture was evaporated todryness and the residue that obtained was co-evaporated twice with drytoluene (2×50 mL) to remove last traces of hexamethyldisilazine. Thesolid that obtained was dried in vacuo for 6 h and used as such forfurther reaction. To a solution of the above trimethylsilyl derivative(12.5 mmol) in dry 1,2-dichlorethane (60 mL) was added 1-O-acetyl2,3,5-tri-O-benzoyl-L-ribofuranose (5.06 g, 10 mmol) and tintetrachloride (1.68 mL, 14.16 mmol) at 10° C. The reaction mixture wasstirred under the atmosphere of argon at room temperature for 6 h. Thereaction mixture was diluted with dichloromethane (200 mL). The organiclayer was washed with sat. sodium bicarbonate (200 mL), water (100 mL)and brine (100 mL), dried over sodium sulfate and concentrated to afoam. The residue was dissolved in dichloromethane (70 mL) and filteredthrough celite to remove tin salts. The crude product was purified bysilica gel flash column chromatography using CH₂Cl₂→EtOAc as the eluent.Pure fractions were pooled and evaporated to give 3.50 g (57%) of awhite foam: ¹H NMR (CDCl₃) δ1.36 (t, 3H, CH₃), 4.30 (m, 2H, CH₂),4.52-4.82 (m, 3H, C_(4′)H and C_(5′)H), 6.08-6.32 (m, 3H, C_(1′)H,C_(2′)H and C_(3′)H) and 7.26-8.08 (m, 16H, C₅H and PhH).

Example 33 1-β-L-Ribofuranosyl-3-hydroxy-1,2-pyrazole-4-carboxamide (50)

[0180] A solution of 49 (3.50 g, 5.71 mmol) in sat. methanolic ammonia(60 mL) was heated at 100° C. for 16 h in a steel bomb. The reactionmixture was cooled to room temperature and concentrated. The residue wastriturated with toluene (2×50 mL) to remove benzamide. The residue wasdissolved in minimum quantity of absolute ethanol and left at roomtemperature overnight. The crystals that obtained was removed byfiltration and the filtrate was concentrated further to yield secondcrop of the product. The combined product recyrstallized once again fromethanol to the solid which was collected by filtration and dried invacuo to yield 1.0 g (68%): mp 178-180° C.; ¹H NMR (Me₂SO-d₆) δ3.37-3.52(m, 2H, C_(5′)H), 3.78 (m, 1H, C_(4′)H), 3.98 (m, 1H, C_(3′)H), 4.19 (m,1H, C_(2′)H), 4.81, 5.05, 5.34 (3br s, 3H, 3 OH, D₂O exchaneable), 5.38(d, 1H, C_(1′)H, J_(1′,2′)=4.2 Hz), 6.98 (bs, 1H, CONH₂), 7.16 (bs, 1H,CONH₂), 8.08 (s, 1H, C₅H) and 10.98 (bs, 1H, C₃OH). Anal. Calc. forC₉H₁₃N₃O₆ (259.22): C, 41.70; H, 5.05; N, 16.21. Found: C, 41.52; H,5.23; N, 16.40.

Example 34 1-Azido-2,3-isopropylidine-b-L-ribofuranose (51)

[0181] To a solution 2,3,5-tri-O-benzoyl-1-azido-b-L-ribofuranose (9.0g, 18.48 mmol) in absolute methanol (60 mL) was added 0.5 M solution ofsodium methoxide (10.0 mL, 5.0 mmol). The reaction mixture was stirredat room temperature overnight. TLC of the reaction (hexane/ethylacetate; 7:3) indicated complete conversion of the starting material toa more polar compound. The reaction mixture was neutralized with dryDowex 50 H⁺ resin and the resin was removed by filtration. The filtratewas evaporated to dryness and dissolved in water (50 mL). The aqueouslayer was extracted with dichloromethane (2×100 mL) to remove methylbenzoate and then the aqueous layer was concentrated in vacuo. Theresidue was further dried over phosphorous pentoxide and used as suchfor the next step of the synthesis without further characterization.

[0182] The above crude product (3.0 g, 17.14 mmol) was suspended in dryacetone (200 mL) and treated with 1,1-dimethoxypropane (50 mL) andvacuum dried Dowex 50 H⁺ (5.0 g) resin. The reaction mixture was stirredat room temperature for 2 h and filtered and the resin was washed withdry acetone (100 mL). The filtrate was evaporated to dryness. Theresidue was purified by flash chromatography over silica gel usingCH₂Cl₂→EtOAc as the eluent. The pure fractions were pooled andconcentrated to give 3.60 g (97%)of product as oil: ¹H NMR (CDCl₃) d,1.44 and 1.27 (2s, 6H, isoporpylident CH₃), 2.70 (br s, 1H, C_(5′)OH,exchangeable), 3.66 (m, 2H, C_(5′)H), 4.34 (m, 1H, C_(4′)H), 4.46 (d,1H, C_(3′)H), 4.72 (d, 1H, C_(2′)H) and 5.50 (s, 1H, Cf_(1′)H).

Example 351-Azido-2,3-O-isopropylidine-5-O-tert-butyldimethylsilyl-b-L-ribofuranose(52)

[0183] To a solution of 1-azido-2,3-O-isopropylidine-b-L-ribofuranose(4.20 g, 20 mmol) in dry DMF (25 mL) was added imidazole (2.38 g, 35.0mmol) and tert-butyldimethylsilyl chloride (4.50 g, 30.0 mmol). Thereaction mixture was stirred at room temperature under argon atmosphereovernight. TLC of the reaction mixture was stirred at indicated completeconversion of the starting material to the product. The solvent wasremoved in vacuo and the residue dissolved in dichloromethane (200 mL).The organic layer is washed with water (100 mL), satd. sodiumbicarbonate (100 mL) and brine (100 mL), dried over sodium sulfate andconcentrated to an oily product. Further purification by silica gelflash column chromatography using hexane/ethyl acetate (9:1) gave 6.22 g(94%) of the titled compound as oil: ¹H NMR (CDCl₃) d 0.07 (s, 6H), 0.9(s, 9H), 1.27 and 1.47 (2s, 6H, isopropylidene CH₃), 3.66 (m, 2H,C_(5′)H), 4.34 (m, 1H, C4′H), 4.46 (d, 1H, C_(3′)H), 4.72 (d, 1H,C_(2′)H) and 5.50 (s, 1H, C_(1′)H).

Example 361-Amino-2,3-O-isopropylidine-5-O-tert-butyldimethylsilyl-β-L-ribofuranose(53)

[0184] To a mixture of 1-azido-2,3-O-isopropylidine-β-L-ribofuranose(6.0 g, 18 mmol) and Pd/C (0.25 g) in MeOH (50 mL) was hydrogenated at50 psi on a parr hydrogenator overnight. The reaction mixture wasfiltered and the catalyst washed with methanol(20 mL). The combinedfiltrate was evaporated to dryness and dried over P2O5 at vacuoovernight and used as such for the next reaction withoutcharacterization. Yield 5.0 g (90%).

Example 37 Ethyl5-amino-(2′,3′-O-isopropylidine-5′-O-tert-butyldimethylsilyl-β-L-ribofuranosyl)imidazole-4-carbozylate(54)

[0185] To a stirred solution of 53 (5.0 g, 16.44 mmol) in dry CH₂Cl₂ (60mL) was added a solution of ethylN-cyano-N-(ethoxycarbonylmethyl)formimidate (4.0 g, 22.18 mmol;Robinson, D. H., et al, J. Chem Soc., Perkin 1, 1715-1717, 1972) during15 min period. The reaction mixture was stirred at room temperatureovernight under argon atmosphere. The reaction was diluted with CH₂Cl₂(100 mL) and the organic layer was washed with sat. NaHCO3 (100 mL),water (50 mL) and brine (50 mL). The organic extract was dried andconcentrated to give a crude product. The crude product was purified byflash chromatography over silica gel using CH₂Cl₂→EtOAc as the eluent.The pure fractions were pooled and evaporated to five 5.50 g (76%) aswhite foam: ¹H NMR (CDCl₃) δ0.28 (m, 6H), 1.1 (m, 9H), 1.55 (m, 9H),4.00 (m, 2H, C_(5′)H), 4.53 (m, 3H), 5.0 (m, 1H), 5.78 (m, 1H), 6.06 (d,1H, C_(1′)H) and 7.44 (s, 1H, C₂H).

Example 385-amino-(2′,3′-O-isopropylidine-5′-O-tert-butyldimethylsilyl-β-L-ribofuranosyl)imidazole-4-carboxamide(55)

[0186] A solution of 54 (5.0 g, 11.33 mmol) in methanolic ammonia (60mL) was heated at 100° C. in a steel bomb for 12 h. The steel bomb wascooled, opened carefuilly and concentrated. The crude product waspurified by flash chromatography over silica gel using CH₂Cl₂→EtOAc asthe eluent. The pure fractions were pooled and evaporated to give 4.0 g(88%) as white foam.

Example 395-Amino-(2′,3′-O-isopropylidine-β-L-ribofuranosyl)imidazole-4-carboxamide(56)

[0187] To a stirred solution of 55 (4.0 g, 9.97 mmol) in dichloromethane(50 mL) was added Et₃N.3HF (50 mmol) at room temperature. The reactionmixture was stirred overnight and evaporated to dryness. The residue waspurified by flash chromatography over silica gel using CH₂Cl₂→EtOAc asthe eluent. The pure fractions were pooled and evaporated to give 2.10 g(71%) as white foam.

Example 40 5-Amino-1-β-L-ribofuranosylimidazole-4-carboxamide (57)

[0188] To a stirred solution of 56 (2.0 g, 6.71 mmol) in dichloromethane(20 mL) was added 90% CF₃COOH (20 mL) at 0° C. The reaction mixture wasstirred at 0° C. for 1 h and evaporated to dryness. The residue wascoevaporated with dry methanol (20 mL). This process was repeated threetimes to remove last traces of TFA. The residue was treated with NH₄OH(10 mL) and evaporated to dryness. The residue was evaporated with dryethanol (3×20 mL). The residue was crystallized from ethanol to give 1.5g (87%) of pure product.

Example 41 Methyl1-β-L-(2′,3′,5′-Tri-O-benzoyl)ribofuranosyl-2-oxo-Δ⁴-imidazoline-4-carboxylate

[0189] A mixture of methyl 2-oxo-Δ⁴-imidazoline-4carboxylate 58 (542 mg,3.82 mmol), hexamethyldisilazane (HMDS, 28 mL) and (NH₄)₂SO₄ (75 mg,0.56 mmol) were heated at reflux. A clear sulution formed in 40 min andthe reaction was maintained at reflux for another 3.5 h. The excess HMDSwas evaporated and the product, a brown oil further dried under vacuumfor 1 h.

[0190] A solution of 1-O-acetyl-2,3,5-O-tri-benzoyl-L-ribofuranose (1.93g, 3.82 mmol) in anhydrous dichloroethane (28 mL) was added to the abovedried silyl base at room temperature followed by dropwise addition ofSnCl₄ (1.39 g, 0.63 mL, 5.35 mmol). After addition, the reaction mixturewas allowed to stay at room temperature overnight (17 h). The reactionmixture was filtered through a silica gel pad flushed with EtOAc. TheEtOAc solution was washed with sat. NaHCO₃, filtered, washed with brinetwice. The organic phase was separated dried over Na₂SO₄, concentrated,and purified by flash chromatography over silica gel using (86% CH₂Cl₂,14% EtOAc) to give 797 mg (36%) of the product as an off-white solid: ¹HNMR (Me₂SO-d₆) δ3.70 (m, 2H), 4.60 (dd, 1H, J_(1′,2′)=12.7, 6.6 Hz,),4.70 (m, 2H), 5,93 (dd, 1H, 5,98 (d, 1H), 6.05 (dd, 1H), 7.46 (m, 6H),7.63 (m, 3H), 7.71 (s, 1H), 7.91 (m, 6H) and 11.15 (s, 1H).

Example 42 1-β-L-Ribofuranosyl-2-oxo-Δ⁴-imidazoline-4-carboxamide (60)

[0191] Compound 59 (1.26 g, 2.15 mmol) was dissolved in methanolicammonia (45 mL, pre-saturated with NH₃ at 0° C.). The solution wassealed in a steel bomb and heated at 95° C. for 15 h. The reactionmixture was cooled to room temperature, the solvent was evaporated, andthe residue washed with CHCl₃ three time to remove the benzamidegenerated from the reaction. The residue was then added with MeOH (15mL) and heated at reflux. CHCl₃ was added to the clear solution atreflux slowly until trace of precipitate generated. The hot mixture wasfiltered quickly by suction and the filtrate solution was evaporated todryness to give a light brown oil. The oil was soaked with anhydrousCH₃CN afforded the product as a light brown solid: Yield 322 mg (58%);mp 174-178° C. ¹H NMR (Me₂SO-d₆) δ3.48 (m, 2H), 3.77 (m, 1H), 3.94 (m,1H), 4.05 (m, 1H), 4.90 (m, 1H), 5.08 (d, 1H), 5.30 (d, 1H), 5.36 (d,1H), 7.30 (s,1H), 7.31 (br s, 2H) and 10.47 (br s, 1H).

Example 43 2,3,5-Tri-O-benzoyl-β-L-ribofuranosyl-1-carbonitrile (61)

[0192] To a stirred mixture of1-O-acetyl-2,3,5-tri-O-benzoyl-β-L-ribofuranose (dried at 60° C., 1 mm,12 h; 12.6 g, 24.9 mmol) in dry dichloromethane (dried over magnesiumsulfate and stored over molecular sieves, 125 mL) at 0-2° C. was addedtrimethylsilyl cyanide (dried over molecular sieves, 24 h; 4.70 mL,37.50 mmol) under argon atmosphere. To this reaction mixture was thenadded stannic chloride (1.0 mL, 8.67 mmol) slowly while maintaining areaction temperature at 0-2° C. The resulting mixture was stirred andmaintained at −5 to 0° C. for an additional 1.5 h. After 2 h, thereaction mixture was added slowly into a vigorous stirring cold (5° C.)10% sodium hydroxide solution (1.5 L) during 30 min period and themixture was maintained at 5-8° C. throughout the addition. The layerswere separated and the organic layer was washed with water (3×500 mL)until neutral and then dried over anhydrous magnesium sulfate. Theorganic extract was filtered and the drying agent was washed withdichloromethane (3×50 mL). The filtrate and washings were combined andthe solution was concentrated (<30° C., 20 mm) to a low volume and theremaining solution was filtered through a bed of celite. Furtherpurification was achieved by silica gell flash column usingdichloromethane as eluent. The dichloromethane solutions were combinedand evaporated (<30° C., 20 mm) to give a white foam. The crude productwas purified by flash chromatography over silica gel usingdichloromethane as the eluent. The pure fractions were combined andevaporated to give a syrup. The syrup was mixed with dry ethanol (100mL) and the mixture was heated (approx. 60° C.) to obtain a homogeneoussolution. Cooling of this solution to room temperature gave whitecrystalline product. The crystalline solid was filtered and washed withcold ethanol and dried over P₂O₅ to give 7.47 g (63%) of 61: mp 55-57°C.; ¹H NMR (CDCl₃) δ4.61 (m, 1H, C_(4′)H), 4.78 (m, 2H, C_(5′)H), 5.00(d, 1H, C_(1′)H), 5.88 (t, 1H, C_(3′)H), 6.05 (m, 1H, C_(2′)H),7.45-8.07 (m, 15H, PhH).

Example 44 2,3,5-Tri-O-benzoyl-β-L (+)-ribofuranosyl allonthioamide (62)

[0193] To a suspension of L-cyanosugar 61 (6.10 g, 12.95 mmol) in dryethanol (105 mL) was passed H₂S for 10 min. To this solution was thenadded N,N-dimethylaminopyridine (DMAP, 158 mg, 1.3 mmol). The reactionwas kept at 15-20° C. and sat. with H₂S during 2½ h period. (Note: Thestarting material which was a suspension was dissolved during the courseof reaction). After 2½ h, the H₂S bubbling was stopped, the reactionmixture was stoppered and allowed to stir at room temperature overnight.The reaction was checked by TLC next day morning (Hexane/EtOAc; 7:3).TLC indicated complete conversion of the starting material to theallothioamide. The reaction mixture was cooled on an ice bath and argonwas bubbled through this for 1 h to remove the excess H₂S. Later thereaction mixture was concentrated on a rotavapor to yield 6.20 g (95%)of a foamy material: ¹H NMR (CDCl₃) δ4.78 (m, 3H, C_(4′)H and C_(5′)H),5.12 (d, 1H, C_(1′)H), 5.72 (t, 1H, C_(3′)H), 5.98 (m, 1H, C_(2′)H),7.45-8.12 (m, 15H, PhH) and (8.50 (br s, 2H, NH₂).

Example 45 Ethyl2-(2′,3′,5′-Tri-O-benzoyl-β-L(+)-ribofuranosyl)thiazole-4-carboxylate(63)

[0194] To a stirred suspension of allothioamide 62 (5.05 g, 10 mmol) indry 1,2-dimethoxyethane (DME, 100 mL) at 0° C. was added of anhydrousNaHCO₃ (8.4 g, 100 mmol). To this suspension under argon was added ofethylbromopyruvate (3.75 mL, 30 mmol) dropwise during 10 min period. Thereaction mixture was stirred at 0° C. for 5 h under argon. The reactionwas analyzed by TLC (Hex/EtOAc; 7:3). TLC indicated traces of startingmaterial. The reaction was left additional 1 h at 0-5° C., by which timemost of the starting material was converted into the product. Then, thereaction mixture was cooled to −15° C. in dry ice/acetone bath. To thereaction mixture was then added dropwise through a dropping funnel asolution of 2,6-lutidine (7.0 mL, 60 mmol) and trifluoroacetic anhydride(4.16 mL, 30 mmol) in dry DME (20 mL) during 15 min period. The reactionmixture temperature was maintained at −15° C. for 2 h under argon. Then,the reaction mixture was filtered and concentrated. The residue thatobtained was dissolved in CH₂Cl₂ (200 mL) and the organic layer waswashed with 5% NaHCO₃ (100 mL), 1N HCl (100 mL), 5% NaHCO₃ (100 mL),water (100 mL) and brine 100 mL), dried and concentrated to a dark redcolor oil. The crude product was purified by silica gel flash columnchromatography using hexane/EtOAc (7:3) as the eluent gave 5.96 g (99%)of pure product: ¹H NMR (CDCl₃) δ1.30 (t, 3H, CH₂CH₃), 4.30 (t, 2H,CH₂CH₃), 4.55-4.78 (m, 3H, C_(4′)H) and C_(5′)H), 5.71 (d, 1H), 5.82 (m,2H), 7.25-8.04 (m, 15H, PhH) and 8.06 (s, 1H, C₅H).

Example 46 β-L (+)-Ribofuranosylthiazole-4-carboxylic acid ethyl ester(64)

[0195] Compound 63 (6.0 g, 10 mmol) was dissolved in dry ethanol (60 mL)(Note: the compound was dissolved by warming with hot air gun). To thissolution under argon was added NaOEt (200 mg, 3.0 mmol) powder. Thereaction mixture was stirred under argon overnight. The reaction waschecked by TLC using hexane/EtOAc 7:3 and EtOAc/MeOH 9:1). TLC hasindicated complete conversion of the starting material to a more polarproduct. Then, the reaction was neutralized with dry Dowex 5x-8 H⁺resin. The resin was removed by filtration and the filtrate wasconcentrated under vacuum on a rotavapor. The brown colored residue wasthen purified by silica gel flash column chromatography usingEtOAc→MeOH. The pure fractions were pooled and concentrated to furnish2.31 g (77%) of pure product. ¹H NMR (CDCl₃) δ1.30 (t, 3H, CH₂CH₃), 3.56(m, 2H, C_(5′)H), 3.86 (m, 2H), 4.0 (m, 1H), 4.26 (t, 2H, CH₂CH₃),4.82-5.04 (3m, 3H, 3 OH), 5.42 (d, 1H, C_(1′)H) and 8.46 (s, 1H, C₅H).

Example 47 β-L(+)-Ribofuranosylthiazole-4-carboxamide (65)

[0196] A solution of 64 (1.0 g, 3.32 mmol) in methanolic ammonia (50 mL)was stirred at room temperature in a steel bomb. After 17 h, the bombwas cooled, opened carefully and the solution was evaporated to aresidue. The residue was chromatographed on a silica gel flash columnchromatography using ethyl acetate and methanol (9:1) as the eluent. Theproduct is crystallized from absolute ethanol. Yield 580 mg (67%): mp146-148° C.; ¹H NMR (Me₂SO-d₆) δ3.48 (m, 2H, C_(5′)H), 3.85 (m, 2H),4.03 (m, 1H), 4.80 (t, 1H, C₅′OH), 4.88 (d, 1H, C_(3′)OH), 5.32 (d, 1H,C_(2′)OH), 5.02 (d, 1H, C_(1′)H, J_(1′,2′)=5.1 Hz), 7.52 (bs, 1H,CONH₂), 7.64 (bs, 1H, CONH₂) and 8.16 (s, 1H, C₅H). Anal calc. forC₉H₁₂N₂SO₅ (260.2): C, 41.53; H, 4.65; N, 10.76; S, 12.32. Found: C,41.73; H, 4.60; N, 10.55; S, 12.25.

Example 48 β-L-Ribofuranosyl-1-carboximidic Acid Methyl Ester (66)

[0197] To a stirred suspension of 2,3,5-tri-O-benzoyl-β-L-ribofuranosylcyanide (14.13 g, 30.0 mmol) in dry methanol (60 mL) was added sodiummethoxide (0.358 g, 6.64 mmol, 0.5 M solution, Fluka) under argonatmosphere. The solution, which became homogeneous in 5 min, was stirredfor 2.5 h at room temperature. The reaction mixture was neutralized withDowex 50W-X8 H⁺ resin (dried at 100° C. under 0.05 mm Hg 16 h; 3.0 g,5.1 molar equiv/g). The resin was filtered and the solvent was removedbelow 40° C. on a rotavapor. The residue that obtained was washed withmethanol. The methanol washings were concentrated to obtain second andthird crops of 66. The three crops were combined and recyrstallized fromdry methanol to provide 4.35 g (66%): mp 140-142° C.; ¹H NMR (CDCl₃)δ3.46 (s, 3H, OCH₃), 3.5-3.80 (m, 5H), 3.98 (d, 1H), 4.98 (br s, 3H) and8.27 (s, 1H, NH).

Example 492-[(Aminocarbonyl)carbonyl]-1-(β-L-ribofuranosyliminomethyl)hydrazine(67)

[0198] Methyl imidate 66 (4.83 g, 25.26 mmol) and oxamidohydrazide (2.68g, 26.00 mmol) were dissolved in dry dimethyl sulfoxide (100 mL). Afterthe reaction solution was stirred for 20 h at room temperature, thesolvent was distilled off at 55° C. in vacuo. The residual solid wassuspended in methanol, and the soluble portion was collected byfiltration (the insoluble solid was found to be unreacted hydrazide) andconcentrated to about 25 mL. Addition of this solution drop-wise intoacetonitrile (500 mL) a white precipitate was obtained: yield 4.35 g(66%); ¹HNMR (Me₂SO-d₆) δ3.47-3.60 (m, 2H), 3.3.60-3.88 (m, 3H), 4.07(d, 1H), 4.15 (d, 1H), 4.85-5.2 (br s, 2H), 7.70, 8.09 (2 br s, 2H) and10.05 (br s, 1H, C═NH).

Example 50 3-β-L-Ribofuranosyl-1,2,4-triazole-5-carboxamide(C-Ribavirin; 68):

[0199] Compound 67 (4.0 g, 15.2 mmol) was heated under vacuum (0.1 mm)at 135° C. for 15 min. After the flask was cooled, the glassy materialwas treated with methanol and heated on a steam bath. During thisprocess a solid started to precipitate. After about 2 h, the solid wasisolated, and a second crop was obtained on concentration of thefiltrate. The total yield of the product was 2.65 g (71%): mp 193-195°C.; ¹H NMR (Me₂SO-d₆) δ3.43 (m, 2H, C_(5′)H), 3,75 (m, 1H, C_(4′)H),3.88 (m, 1H, C_(3′)H), 4.12 (m, 1H, C_(2′)H), 4.57 (d, 1H, C_(1′)H,J_(1′,2′)=5.7 Hz), 7.62 (bs, 1H, CONH₂), 7.86 (bs, 1H, CONH₂) and 10.0(bs, 1H, NH), Anal. Calc. for C₈H₁₂N₄O₅ (244.2): C, 39.35; H, 4.95; N,22.94. Found: C, 39.38; H, 4.73; N, 22.43.

Example 51 5-O-Trityl-2,3-O-isopropylidene-b-L-ribofuranose (69)

[0200] To a solution of 2,3-O-isopropylidene-b-L-ribofuranose (10.5 g,55.26 mmol) in dry pyridine (100 mL) under argon was added catalyticamount of DMAP (12.2 mg, 0.1 mmol). To this stirred solution was thenadded trityl chloride (15.56 g, 56.0 mmol). The reaction mixture wasstirred under argon atmosphere overnight at room temperature. Pyridinewas removed under vacuum and the residue was dissolved in CH₂Cl₂ (250mL) and the organic layer was washed with 10% NaHCO₃ solution (2×100 mL)and brine (100 mL). The organic layer was dried over Na₂SO₄ andconcentrated in vacuo. The residue that obtained was purified by silicagel flash column using Hexane→EtOAc as the eluent. Pure fractions werepooled and concentrated to give 15.74 g (69%) of product: ¹H NMR (CDCl₃)δ1.27 and 1.41(2s, 6H, isopropylidene CH₃), 3.25-3.56 (m, 2H, C_(5′)H),3.86 (m, 2H), 4.0 (m, 1H), 4.70 (m, 1 H), 5.24 (d, 1H, J_(1′,2′)=3.50Hz, C_(1′)H) and 7.17-7.35 (m, 15H, PhH).

Example 52 3-Ethoxycarbonyl-2-oxopropylidenetriphenyl-phosphorane (70)

[0201] A solution of {3-(ethoxycarbonyl)-2-oxopropyl}triphenylphosphonium chloride (21.34 g, 500 mmol) in water (450 mL) was added toa solution of sodium carbonate (3.1 g, 25.0 mmol) in 10 min (Note: Awhite precipitate was obtained immediately after the addition). Thisreaction mixture was stirred at room temperature overnight. Theprecipitate that obtained was filtered off through a sintered funnel.The precipitate was dissolved in dichloromethane (100 mL), dried oversodium sulfate and concentrated to yield a white solid 18.13 g (93%).This material was dried over phosphorus pentoxide overnight. ¹H NMR(CDCl₃) δ1.26 (t, 3H), 3.34 (s, 2H), 3.76-3.84 (d, 1H) 4.19 (m, 2H) and7.48-7.68 (m, 15H, PhH).

Example 53 Ethyl 4-(2′,3′-O-Isopropylidene-5′-O-trityl-α-andβ-L-ribofuranosyl)-3-oxobutanoate (71)

[0202] A mixture 70 (10.9 g, 25.23 mmol) and3-ethoxycarbonyl-2-oxopropylidenetriphenyl-phosphorane (11.8 g, 30 mmol)in anhydrous acetonitrile (30 mL) was refluxed for 90 h. The solvent wasevaporated under reduced pressure and the residue was subjected to asilica gel flash column chromatography. Elution with hexane-ethylacetate (9:1) gave the product (β:α ca.2:1) as a foam (10.15 g, 74%).

Example 54 Ethyl 2-Diazo-4-(2′,3′-O-isopropylidene-5′-O-trityl-α- and-β-L-ribofuranosyl)-3-oxobutanoate (72)

[0203] Triethylamine (1.83 g, 18.1 mmol) and toluene-p-sulphonyl azide(10 mL) were sequentially added to a solution of 71 (9.85 g, 18.08 mmol)in anhydrous acetonitrile (50 mL). The mixture was kept at roomtemperature for 30 min. The solvent was then evaporated under reducedpressure and the residue was subjected to a silica gel flash columnchromatography. Elution with hexane-ethyl acetate (9:1) gave 8.90 g(86%) of 72 (β:α ca. 1:1) as a foam.

Example 55 Ethyl4-hydroxy-3-(2′,3′-O-isopropylidene-5′-O-trityl-β-L-ribofuiranosyl)pyrazole-5-carboxylate(73)

[0204] A solution of 72 (8.53 g, 14.92 mmol) in dry DME (60 mL) wasadded dropwise to a stired ice-cold suspension of sodium hydride (NaH)(60% dispersion; 1.80 g, 75.0 mmol) in dry DME (60 mL) under argonduring 30 min. The reaction temperature was raised gradually to 20° C.,and the mixture was stirred additional 3 h at room temperature. Thereaction mixture was analyzed by TLC using hexane/EtOAc (3:1) ordichloromethane/EtOAc (9:1). TLC indicated completion of the reaction. Asolution of acetic acid (4.50 mL, 75.0 mmol) in DME (10 mL) was thenadded dropwise to the stirred ice-cold reaction mixture. The solvent wasevaporated under reduced pressure to give a residue to which water (50mL) and diethyl ether (100 mL) were added. The ethereal layer wasseparated, dried over anhydrous sodium sulfate and concentrated. Theresidue was subjected to silica gel flash column chromatography withhexane-ethyl acetate (3:1) as the eluent. Pure fractions were collectedand evaporated to give 73 as a mixture of β:α (6.40 g, 73%): ¹H NMR(CDCl₃) δ1.31 (t, 3H), 1.42-1.65 (m, 6H), 3.19-3.27 (m, 2H), 4.44-4.75(m, 3H), 4.75 (m, 1H), 5.19 (d, 1H), 6.99 (br s, OH, exchangeable),7.26-7.51 (m, 15H, PhH).

Example 564-Hydroxy-3-(2′,3′-O-isopropylidene-5′-O-trityl-β-L-ribofuranosyl)pyrazole-5-carboxamide(74)

[0205] A solution of the ester 73 (6.30 g, 10.7 mmol) in dry methanolicammonia (70 mL) was heated at 90-95° C. in a steel bomb for 12 h. Thesolvent was evaporated under reduced pressure and the residue wassubjected to silica gel flash column chromotography using hexane/ethylacetate (3:2) as the eluent. The required fractions were pooled andevaporated to give 4.54 g (78%) of the product as a glass containing amixture of β:α. ¹H NMR (CDCl₃) δ1.40-1.62 (2s, 6H), 3.11-3.24 (m, 2H),4.37 (m, 1H), 4.65 (m, 1H), 5.11 (dd, 1H), 5.27 (d, 1H), 6.99 (br s, OH,exchangeable) and 7.23-7.50 (m, 17H).

Example 57 3-β-L-Ribofruanosyl-4-hydroxypyrazole-5-carboxamide(L-Pyrazomycin; 75)

[0206] A solution of 74 (4.40 gm, 8.13 mmol) in 90% CF₃CO₂H (20 mL) wasstirred at room temperature for 45 min. Then the solvent was removed at5° C. under reduced pressure to give white solid (1.90 g, 90.48%). Theresidue that obtained was chromatographed on silica gel flash columnwith EtOAc-iPrOH-H₂O (4:1:2) as the eluent. Fractions containing thepure compound b and a isomers were pooled separately and evaporated at<20° C. Recrystallization from water afforded 800 mg of pure β isomer:mp 111-113° C.; ¹H NMR of β isomer (D₂O) δ3.73-3.78 (m, 2H), 4.0 (m,1H), 4.19 (m, 1H), 4.35 (m, 1H) and 4.90-4.93 (d, 1H, J_(1′,2′)=7.42Hz). Anal. Calc. for C₉H₁₃N₃O₆ (259.22): C, 41.70; H, 5.05; N, 16.21.Found: C, 41.88; H, 5.04; N, 16.58. Isolated yield of α:β mixture 1.90g, (90%).

[0207] 100 mg of isomer was isolated as foam; ¹H NMR of α isomer (D₂O)δ3.65-3.85 (m, 2H), 4.06-4.11 (m, 1H), 4.32-4.41 (m, 2H), and 5.20 (d,1H, J_(1′,2′)=3.30 Hz). Anal. Calc. for C₉H₁₃N₃O₆: C, 41.70; H, 5.05; N,16.21. Found: C, 41.91; H, 5.08; N, 16.02.

[0208] 1.0 gm of inseparable mixture of L-pyrazomycin was also isolated.

[0209] The purity of the α:β isomers is also established by C18 reversephase HPLC using the gradient of acentonitrile 0-10% in water. Theretention time of α isomer is Rt 5.716 and the β isomer 7.135. Thepurity of β and α mixture of L-pyrazomycin is found to be greater than99.0% by HPLC.

Example 58 Preparation of 2,5-Anhydro-L-alloamidine hydrochloride (76)

[0210] Methyl 2,5-anhydro-L-allonimidate (3.82 g, 20.0 mmol) andammonium chloride (1.07 g, 20.0 mmol were dissolved in methanolicammonia (60 mL, saturated at dry ice-acetone temperature for 1 h). Laterthis mixture was allowed stir at room temperature in a thick walledsteel bomb for 16 h at room temperature. The steel bomb was cooled,opened carefully and the solution was evaporated to dryness. Theresulting solid was dried to yield 4.10 g of the titled compound inquantitative yield.

Example 59 2-(β-L-Ribofuranosyl)pyrimidine-6(1H)-oxo-4-carboxylic acid(77)

[0211] To a solution of 2,5-anhydro-L-alloamidine hydrochloride (4.0 g,18.66 mmol) in water (60 mL) was added sodium hydroxide (1N, 20 mL, 20.0mmol) and ethyl sodium oxaloacetate (4.20 g, 20.0 mmol). The reactionmixture was allowed to stir room temperature at 16 h at room temperatureand was subsequently neutralized to pH 2 with H⁺ resin (Dowex 50W-X8).The reaction mixture was filtered and concentrated to a minimum volume.Silica gel was added and evaporated to dryness. The resultant powder wasplaced on the top of a flash column and eluted with ethylacetate/acetone/methanol/water (3/1/1/1) mixture until the faster movingcompound was eluted. The column was then eluted with methanol and thefractions containing the compound were pooled and the methanol wasremoved to yield artan color hygroscopic compound. Isolated yield 4.50 g(89%). This compound was used as such for the next step withoutcharacterization.

Example 60 Ethyl 2-(β-L-Ribofaranosyl)pyrimidine-6(1H)-oxo-4-carboxylate(78)

[0212] A thoroughly dried suspension of the acid 77 (4.50 g, 16.5 mmol)in of dry ethanol (100 mL) was cooled in an ice bath and dry hydrogenchloride gas was bubbled for 5 min. To this reaction mixture was addedtriethyl orthoformate (20 mL) and the mixture was allowed to stir for 24h at room temperature. The solvent was removed under vacuum and theresultant dark colored solid was purified further by silica gel flashcolumn chromatography using dichloromethane/methanol (9/1) mixture. Purefractions were pooled and concentrated to yield 4.55 g (92%) of a solidcompound. Since this compound was found to be impure, it is furtherconverted to the corresponding tetra acetate in 47% yield. The tetraacetate was purified by column chromatography.

Example 61 2-(β-L-Ribofuranosyl)pyrimidine-6(1H)-oxo-4-carboxamide (79)

[0213] A solution of the above tetra acetate ester (1.80 g, 4.22 mmol)in sat. methanolic ammonia (60 mL) was heated at 100° C. in a steel bombfor 17 h. The reaction mixture was cooled and concentrated to yield awhite solid. The solid was further triturated with ethyl acetate andfiltered. The solid was recyrstallized from absolute ethanol to provide0.83 g (82%) of pure product as white solid: mp 200-202° C.; ¹H NMR(Me₂SO-d₆) δ3.35-3.57 (m, 2H, C_(5′)H), 3.84 (m, 1H, C_(4′)H), 3.98 (m,1H, C_(3′)H), 4.22 (m, 1H, C_(2′)H), 4.75 (t, 1H, C_(5′)OH, D₂Oexchangeble), 4.80 (d, 1H, C_(1′)H, J_(1′,2′)=5.77 Hz), 4.89 (d, 1H,C_(3′)OH, D₂O exchangeable), 5.15 (d, 1H, C_(2′)OH, D₂O exchangeable),7.85 (d, 1H), 7.98 (bs, 1H, CONH₂), 8.19 (bs, 1H, CONH₂) and 9.0 (d, 1H,NH). Anal. Calc. for C₁₀H₁₃N₃O₄ (239.23): C, 44.28; H, 4.83; N, 15.49.Found: C, 44.58; H, 5.17; N, 15.28.

Example 63 Methyl β-L-arabinopyranoside (81)

[0214] To a suspension of L-arabinose (100 g, 667 mmol) in anhydrousMeOH (450 mL ) was added a HCl/MeOH solution (7.3 g dry HCl in 50 mLMeOH) at room temperature under argon atmosphere. The mixture wasrefluxed for 2 h and cooled down to room temperature. The solution wasconcentrated to about ¾ of its volume to give a suspension. The solidprecipitated was filtered and washed with cold MeOH (20 mL) to give thefirst crop as a crystalline powder (35.23 g). The filtrate wasconcentrated (35° C.) to ¼ of its volume. The solid precipitated wasfiltered, washed and dried as above to give the second crop (9.66 g) asa colorless crystalline powder. The concentration and filtration wererepeated to afford additional 28.31 g of the product (total 73.2 g,67%). ¹H NMR (D₂O) δ3.30 (s, OCH₃, 3H), 3.56 (dd, 1H, H₅), 3.73 (m, 1H,H₄), 3.77 (dd, 1H, H₅), 3.82 (bs, 1H, H₂), 4.73 (m, 1H, H₁).

Example 63 Methyl 3,4-isopropylidene-β-L-arabino-pyranoside (82)

[0215] To the mixture of methyl β-L-arabinopyranoside 81 (23.33 g,142.26 mmol) and dimethoxypropane (55 mL, 448 mmol) in dry DMF (185 mL)was added Amberlyst 15 (H+ form, 1.42 g) and the suspension was stirredat room temperature for 18 h. The solution was evaporated to give asyrup, which was dissolved in EtOAc (200 mL) and washed with brine (50mL), sat. NaHCO₃ solution and brine (20 mL). The aqueous washings werecombined and extracted with EtOAc (5×20 mL), which was washed withNaCl/H₂O and combined with the organic solution. The EtOAc solution wasdried over anhydrous Na₂SO₄ and evaporated to dryness to give a syrup(29.2 g, quant.). ¹H NMR (CDCl₃) δ1.36 and 1.53 (2s, 6H,isopropylidene-CH₃), 2.43 (d, 1H, 2′-OH), 3.44 (s, 3H, OCH₃), 3.78 (m,1H, H₂), 3.93 (s, 2H, H₅), 4.15-4.25 (m, 2H, H₃ & H₄), 4.71 (d, 1H, H₁).

Example 64 Methyl3,4-isopropylidene-2-o-[(methylthio)thiocarbonyl]-β-L-arabino-pyranoside(83)

[0216] The above syrup 82 (29.2 g, 142.26 mmol) was dissolved inanhydrous THF (190 mL) and cooled to 0° C. To the solution was added NaH(55-65%, 6.9 g, 172.5 mmol) slowly under argon atmosphere. Thesuspension was refluxed for 2 h and cooled to 0° C. To the mixture wasadded carbon disulfide (21 mL, 349.14 mmol) and the resultant darkmixture was stirred at room temperature for 2 h. To the mixture wasadded methyl iodide (12.4 mL, 160.64 mmol) at 0° C. and the mixture wasstirred for 16 h. The mixture was poured into ice-water (300 mL) andextracted with EtOAc (3×50 mL). The EtOAc solution was dried andevaporated until crystals precipitated. The suspension was left in arefrigerator for 16 h. The crystals were filtered and washed with hexaneto give the first crop (21.61 g) as a yellowish powder. The filtrate wasconcentrated, kept at 0° C. overnight and filtered to give the secondcrop (16.51 g). This was repeated two more times to give additional 1.44g of the product (39.62 g, two steps from 81 94.7%). Mp 127-130° C. ¹HNMR (CDCl₃) δ1.39 and 1.55 (2s, 6H, isopropylidene-CH₃), 2.60 (s, 3H,SCH_(3′)), 3.40 (s, 3H, OCH₃), 4.01 (s, 2H, H₅), 4.30 (m, 1H, H₄), 4.50(dd, 1H, H₃), 4.98 (d, 1H, H₁), 5.78 (dd, 1H, H₂),

Example 65 Methyl 2-deoxy-β-L-erythro-pentopyranoside (84)

[0217] Compound 83 (40 g, 136 mmol) and AIBN (24.61 g, 150 mmol) weredissolved in dry dioxane (400 mL) by heating in an oil bath (100° C.).The mixture was bubbled with argon atmosphere at 100° C. for 15 minfollowed by addition of diphenylsilane (51.4 mL, 272 mmol). Thetemperature of the oil bath was raised to 130° C. and the mixture wasrefluxed for 16 h. Additional diphenylsilane (2 mL, 10.8 mmol) and AIBN(1.27 g, 7.7 mmol) were added and refluxing was continued for additional5 h. Additional AIBN (0.2 g, 1.2 mmol) was added and refluxing wascontinued for additional 1 h. The mixture was cooled and evaporated togive compound 84 as a syrup, which was mixed with80% HOAc (544 mL) andstirred at room temperature for 16 h. The mixture was evaporated to givea syrup which was partitioned between water and ether. The aqueous layerwas washed with ether and the combined organic layer was extracted withwater. The aqueous solution was evaporated to give compound 85 as asyrup (16.36 g, 81.4% for two steps from 83). ¹H NMR (CDCl₃) δ), 1,89(dd, 2H, H₂). 2.30. (d, 1H, OH), 2.47 (d, 1H, OH), 3.35 (s, 3H,OCH_(3′)), 3.88-3.69 (m, 3H, H₄ & H₅) 4.03 (m, 1H, H₃), 4.79 (t, 1H,H₁).

Example 66 2′-deoxy-β-L-erythro-pentose (86)

[0218] Compound 85 (16.36 g, 110.5 mmol) was dissolved in 0.8 M HClaqueous solution (546 mL) and the resultant mixture was stirred at roomtemperature for 72 h. The mixture was neutralized with 1N NaOH aqueoussolution to PH 6-7 and was evaporated to give a syrup. The crude waspurified on a silica gel column (4×15 cm) eluted with CH₂Cl₂/MeOH(1:0 to95:5) The proper fractions were evaporated to give compound 86 as asyrup (10.53 g, 71.1%).

Example 67 Methyl 2′-deoxy-β-L-erythro-pentose (87)

[0219] Compound 86 (15.68 g, 117.0 mmol) was dissolved in dry MeOH (342mL) and to the resultant solution was added 1% HCl/MeOH (35 mL). Thesolution was kept at ROOM TEMPERATURE for 1 h and neutralized with Py(55 mL) at 5° C. to PH ˜6. The mixture was evaporated with silica geland purified on a silica gel column (1×5 cm) eluted withCH₂Cl₂/MeOH(98:2 to 96:4) to give compound 87 as a syrup (13.94 g,80.5%). ¹H NMR (CDCl₃) δ2.22-2.44 (m, 2H, H₂), 3.50 and 3.59 (2s, 3H,OCH₃), 3.75-3.88 (m, 2H, H₅), 4,26 (m, 1H, H₄), 4.66 (m, 1H, H₃), 5.25(t, 1H, H₁).

Example 68 Methyl 2′-deoxy-3,5-di-O-p-toluoyl-L-erythro-pentose (88)

[0220] Compound 87 (9.00 g, 60.8 mmol) was dissolved in pyridine (180mL) and cooled in an ice-water bath. To this cold solution was addedtoluoyl chloride (18 mL, 00 mmol) in 30 min and the resultant solutionwas stirred at room temperature for 16 h. The mixture was evaporated todryness. The mixture was extracted with EtOAc, washed with brine, driedand evaporated. The crude product was purified on a silica gel column(3×15 cm) using hexane/EtOAc (1:0 to 5:1) as the eluent. Evaporation ofthe proper fractions gave compound 88 as a syrup (22.63 g, 97%). ¹H NMR(CDCl₃) δ2.40 (2s, 6H, 2xCH₃), 3.35 (s, 3H, OCH₃ of β-anomer), 3.41 (s,3H, OCH₃ of α-anomer), 4.6-4.5 (m, H₄ and H₅ of both anomers), 5.19 (d,1H, H₁ of α-anomer), 5.21 (dd, 1H, H₁ of β-anomer), 5.41 (m, 1H, H₃ ofα-anomer), 5.59 (m, 1H, H₃ of β-anomer), 7.18-8.02 (m, 8H, Aromatic),

Example 68 2′-Deoxy-3′,5′-di-O-p-toluoyl-α-L-erythro-pentofuranosylchloride(13)

[0221] Compound 88 (22 g, 57.3 mmol) was dissolved in dry ether (200 mL)and the solution was cooled to 0° C. in an ice bath. To the solution wasbubbled dry HCl for ˜5 min until the mixture crystallized. The reactionmixture was then kept in a refrigerator overnight. The solid thatprecipitated was filtered and washed with cold ether. The solid wasimmediately dried under vacuum over NaOH to give compound 13 as acolorless crystalline powder (19.28 g). The filtrate was concentratedand treated with HCl and kept in a refrigerator overnight. Filtration,washing and drying gave additional 1.2 g of product (total 20.48 g,92%), mp 118-121° C. ¹H NMR (CDCl₃) δ2.39 (2s, 6H, aromatic-CH₃), 2.82(m, 2H, H₂), 4.65 (m, 2H, H₅), 4.86 (q, 1H, H₄), 5.57 (m, 1H, H₃), 6.48(d, 1H, H₁), 7.25 (2d, 4H, aromatic-H), 7.95 (2d, 4H, aromatic-H).

Example 69 Methyl 1-(2′-deoxy-3′, 5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)-1,2,4-triazol-5-carboxylate(89), Methyl1-(2′-deoxy-3′,5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)-1,2,4-triazole-2-carboxylate(90) and Methyl1-(2′-deoxy-3′,5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)-1,2,4-triazole-3-carboxylate(91)

[0222] To a solution of methyl 1,2,4-triazole-3-carboxylate (1.27g, 10mmol) in dry acetonitrile (50 mL) was added sodium hydride (60% in oil,0.5 g, 12.5 mmol). The mixture was stirred at room temperature for 30min. Dry and powdered chloro sugar 13 was added and the suspension wasstirred at room temperature for 16 h. The mixture was evaporated to givea residue which was partitioned between water/EtOAc and extracted inEtOA. The aqueous solution was extracted with EtOAc. The combined EtOAcsolution was washed with brine and evaporated to dryness. The mixturewas purified on a silica gel column (3×20 cm) using EtOAc/hexane (1.2:1)as the eluent to give 89 (1.72 g), 90 (0.98 g) and 91 (0.45 g).

[0223]¹H NMR (CDCl₃) 89: δ2.52 (2s, 6H, CH₃), 2.82 (m, 1H, H_(2′)), 3.45(m, 1H, H_(2′)), 4.60 (dd, 1H, H_(5′)), 4.72 (dd, 1H, H_(5′)), 4.76 (m,1H, H_(4′)), 6.03 (m, 1H, H_(3′)), 7.29-7.38 (m, 5H, aromatic-H andH_(1′)), 7.97-8.12 (m, 5H, aromatic-H and C₅H). 90: δ2.50 & 2.53 (2s,6H, CH₃), 2.95 (m, 1H, H_(2′)), 3.20 (m, 1H, H_(2′)), 4.09 (s, 3H,OCH_(3′)), 4.72 (m, 3H, H_(4′) & H_(5′)), 5.83 (m, 1H), H_(3′)), 6.47(t, 1H, H_(1′)), 7.36 (dd, 4H, aromatic-H), 8.02 (dd, 4H, aromatic-H),8.51 (s, 1H, C₅H). 91: δ2.53 (m, 7H, H_(2′) & 2xCH₃), 3.16 (m, 1H,H_(2′)), 4.13 (s, 3H, OCH_(3,)), 4.69-4.85 (m, 3H, H_(4′) & H_(5′)),5.73 (m, 1H, H_(3′)), 6.88 (q, 1H, H_(1′)), 7.35 (dd, 4H, aromatic-H),7.94 & 8.05 (dd, 4H, aromatic-H), 8.76(s, 1H, C₅H).

Example 701-(2′-Deoxy-β-L-erythro-pentofuranosyl)-1,2,4-triazole-5,-carboxamide(92)

[0224] A mixture of 89 (1.77 g, 3.70 mmol) and saturated methanolicammonia solution (40 mL) was heated in a steel bomb at 55° C. for 16 h.After cooling, the solution was evaporated with silica gel and purifiedon a silica gel column eluted with CH₂Cl₂/MeOH (10:1) to give compound92 as a colorless powder (297 mg, 35%). ¹H NMR (DMSO-d₆): δ2.27 (m, 1H,H_(2′)), 2.60 (m, 1H, H_(2′)), 3.32 (m, 1H, H_(5′)), 3.48 (m, 1H,H_(5′)), 3.80 (m, 1H, H_(4′)), 4.41 (m, 1H, H_(3′)), 7.12 (t, 1H,H_(1′)), 8.06 (s, 1H, NH), 8.14 (s, 1H, C₅H), 8.27 (s, 1H, NH).

Example 711-(2′-Deoxy-β-L-erythro-pentofuranosyl)-1,2,4-triazole-3-carboxamide(93)

[0225] A mixture of 91 (0.45 g, 0.94 mmol) and saturated methanolicammonia solution (20 mL) was heated in a steel bomb at 55° C. for 16 h.After cooling, the solution was evaporated to dryness. The residue waspurified on a silica gel column using CH₂Cl₂/MeOH (10:1) as the eluentto give 93 (54 mg, 25%). ¹H NMR (DMSO-d₆): δ2.24 (m, 1H, H_(2′)), 2.38(m, 1H, H_(2′)), 3.61 (m, 2H, H_(5′)), 3.85 (m, 1H, H_(4′)), 4.30 (m,1H, H_(3′)), 6.70 (t, 1H, H_(1′)), 7.94 (s, 1H, NH), 8.33 (s, 1H, NH)8.98 (s, 1H, C₅H).

Example 721-(2′-Deoxy-3′,5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)-2,4-dicyanopyrrole(94)

[0226] To a solution of 2,4-dicyanopyrrole (302 mg, 2.58 mmol) in dryacetonitrile (25 mL) was added sodium hydride (60% in oil, 125 mg, 2.6mmol). The mixture was stirred at room temperature for 30 min. Thechloro 13 (1 g, 2.58 mmol) was added and the suspension was stirred atroom temperature for 16 h. The mixture was evaporated to give a solidresidue which was partitioned between water and EtOAc. The aqueoussolution was extracted with EtOAc. The combined EtOAc extract was washedwith water and brine, dried and evaporated to dryness. The product waspurified on silica gel column (3×20 cm) using hexane/EtOAc (5:2) aseluent to give 94 as an oil (605 mg, 50%). ¹H NMR (CDCl₃): δ2.29 (s, 3H,aromatic-CH₃), 2.55 (s, 3H, aromatic-CH₃), 2.67 (m, 1H, H_(2′)), 2.98(m, 1H, H_(2′)), 4.74-4.89 (m, 3H, H_(4′) & H_(5′)), 5.77(m, 1H,H_(3′)), 6.36 (t, 1H, H_(1′)), 7.18 (s, 1H, C₅H), 7.38 (m, 4H,aromatic-H), 7.68 (s, 1H, C₃H), 7.97 (d, 2H, aromatic-H), 8.05 (d, 2H,aromatic-H).

Example 73 1-(2′-Deoxy-β-L-erythro-pentofuranosyl)-2,4-dicyanopyrrole(95)

[0227] A mixture of 94 (605 mg, 1.29 mmol) and saturated methanolicammonia solution (20 mL) was heated in a steel bomb at 65° C. for 16 h.After cooling, the solution was evaporated to dryness. The crude productwas purified on a silica gel column eluted with CH₂Cl₂/MeOH (10:1) togive 95 (158 mg, 52%). ¹H NMR (CD₃OD): δ2.55 (m, 2H, H_(2′)), 3.82 (m,2H, H_(5′)), 4.08 (m, 1H, H_(4′)), 4.53 (m, 1H, H_(3′)), 6.38 (t, 1H,H_(1′)), 7.37 (s, 1H, C₅H), 8.19 (s, 1H, C₃H).

Example 741-(2′-Deoxy-β-L-erythro-pentofuranosyl)pyrrole-2,4-dicarboxamide (96)

[0228] To a solution of 95 (90 mg, 0.385 mmol) in aqueous NH₄OH solution(29.6%, 9 mL) was added H₂O₂. The solution was stirred at roomtemperature for 2 h and evaporated to dryness. The residue was purifiedon a silica gel column eluted with CH₂Cl₂/MeOH (10:1) to give Compound96 (75 mg, 72%). ¹H NMR (CD₃OD): δ2.31 & 2.61 (m, 2H, H_(2′)), 3.89 (m,2H, H_(5′)), 4.04 (m, 1H, H_(4′)), 4.45 (m, 1H, H_(3′)), 6.93 (t, 1H,H_(1′)), 7.24 (s, 1H, C₅H), 8.09 (s, 1H, C₃H).

Example 75 Methyl1-(2′-deoxy-3,′,5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)pyrazole-3,5-dicarboxylate(97)

[0229] To a solution of methyl pyrazole-3,5-dicarboxylate (458 mg, 2.5mmol) in dry acetonitrile (25 mL) was added sodium hydride (60% in oil,144 mg, 3.0 mmol). The mixture was stirred at room temperature for 30min. The chloro sugar 13 (970 mg, ˜95%, 2.5 mmol) was added and thesuspension was stirred at room temperature for 4 h. The mixture wasevaporated to dryness and the residue was purified on silica gel column(3×7 cm) using hexane/EtOAc (5:2) as the eluent to give 97 as an oil(470 mg, 35%). ¹H NMR (CDCl₃): δ2.40 (d, 6H, aromatic-CH₃), 2.70 (m, 1H,H_(2′)), 3.60 (m, 1H, H_(2′)), 3.93 (d, 6H, OCH₃), 4.48-4.65 (m, 3H,H_(4′) & H_(5′)), 5.89(m, 1H, H_(3′)), 7.18-7.29 (m, 5H, aromatic-H &H_(1′)), 7.38 (s, 1H, C₄H),7.90 (m, 4H, aromatic-H).

Example 761-(2′-Deoxy-β-L-erythro-pentofuranosyl)pyrazole-3,5-dicarboxamide (98)

[0230] A mixture of 97 (270 mg, 0.51 mmol) and saturated methanolicammonia solution (20 mL) was heated in a steel bomb at 100° C. for 16 h.After cooling, the solution was evaporated and purified on a silica gelcolumn using CH₂Cl₂/MeOH (10:1) to give 98 as a colorless powder (189mg, 73%). ¹H NMR (DMSO-d₆): δ2.25 (m, 1H, H_(2′)), 2.89 (m, 1H, H_(2′)),3.42 (m, 1H, H_(5′)), 3.59 (m, 1H, H_(5′)), 3.86 (q, 1H, H_(4′)), 4.55(m, 1H, H_(3′)), 4.77 (t, 1H, OH), 5.27 (d, 1H, OH), 7.17 (t, 1H,H_(1′)), 7.29 (s, 1H, C₄H), 7.51 (s, 1H, NH), 7.66 (s, 1H, NH), 7.80 (s,1H, NH), 8.19 (s, 1H, NH).

Example 77 Methyl1-(2′-deoxy-3′,5′-di-O-p-toluoyl-β-L-erythro-pentofuranosyl)pyrazole-4-carboxylate(99)

[0231] To a solution of methyl pyrazole-4-carboxylate (315 mg, 2.5 mmol)in dry acetonitrile (30 mL) was added sodium hydride (60% in oil, 144mg, 3.0 mmol). The mixture was stirred at 50° C. for 15 min. The chlorosugar 13 (1 g, ˜95%, 2.5 mmol) was added and the suspension was stirredat room temperature for 2 h. The mixture was evaporated to give aresidue which was partitioned between water and EtOAc. The aqueoussolution was extracted with EtOAc. The combined EtOAc extract was washedwith water and brine, dried over NaSO₄ and evaporated to dryness. Theresidue was purified on silica gel column (3×12 cm) using hexane/EtOAc(4:1) to give 99 as a crystalline powder (549 mg, 46%). ¹H NMR (CDCl₃):δ2.40 (d, 6H, aromatic-CH₃), 2.72 (m, 1H, H_(2′)), 3.16 (m, 1H, H_(2′)),3.79 (d, 3H, OCH₃), 4.51-4.62 (m, 3H, H_(4′) & H_(5′)), 5.77 (m, 1H,H_(3′)), 6.20 (t, 1H, H_(1′)), 7.24 (m, 4H, aromatic-H), 7.92 (m, 5H,aromatic-H & C₅h), 8.10 (s, 1H, C₃H).

Example 78 1-(2′-Deoxy-β-L-erythro-pentofuranosyl)pyrazole-4-carboxamide(100)

[0232] A mixture of 99 (500 mg, 1.046 mmol) and saturated methanolicammonia solution (30 mL) was heated in a steel bomb at 100° C. for 16 h.After cooling, the solution was evaporated and the residue was purifiedon a silica gel column using CH₂Cl₂/MeOH (10:1) to give 100 as yellowfoam (50 mg, 20%). ¹H NMR (DMSO-d₆): δ2.30 (m, 1H, H_(2′)), 2.56 (m, 1H,H_(2′)), 3.41-3.56 (m, 2H, H_(5′)), 3.84 (m, 1H, H_(4′)), 4.36 (m, 1H,H_(3′)), 4.88 (bs, 1H, OH), 5.32 (bs, 1H, OH), 6.11 (t, 1H, H_(1′)), ),7.08 (s, 1H, NH), 7.63 (s, 1H, NH), ), 7.90 (d, 1H, C₅H), 8.36 (d, 1H,C₃h). 7.80 (s, 1H, NH), 8.19 (s, 1H, NH).

Example 79 Methyl-α-L-lyxopyranoside (102)

[0233] To a methanolic HCl solution [600 mL, 0.5% w/v, prepared in situby reaction of acetyl chloride (6.0 mL)] was added L-lyxose (101, 118 g,786 mmol and refluxed for 5 h [the reaction was complete in 4 h (by TLC30% MeOH/CH₂Cl₂) and continued for additional 1 h (total 5 h)] underexclusion of moisture (protected by CaCl₂ guard tube). The reactionmixture was neutralized with pre-treated¹ amberlite basic resin IRA 410(100.0 g) for 10 min under stirring. The resin was filtered and washedwith methanol (3×50 mL). The combined washings were evaporated to obtaina color less syrup. The syrup was co-evaporated with ethyl acetate (2×50mL) and finally recrystallized (by scratching the side of RB flask orsonication) from ethyl acetate (500 mL) to obtain white crystallineproduct 102 (87 g, 67% total from both 1 and 2 crop). ¹H NMR (300 MHz,(CD₃)₂CO): δ3.15 (bs, 3H, OH), 3.41 (s, 3H, OCH₃), 3.48 (m, 1H),3.66-3.72 (m, 2H), 3.73-3.87 (m, 2H), 4.64 (d, 1H, H-_(5′), J=2.7 Hz).

Example 80 Methyl-2,3-O-isopropylidene-α-L-lyxopyranoside (103)

[0234] To a suspension of 102 (69 g, 420.0 mmol) in a mixture of2,2-dimethoxy propane (200.0 mL) and anhydrous acetone (200.0 mL) wasadded a solution (4M) of HCl in dioxane (4.0 mL) and the reactionmixture was stirred at 25° C. for 16 h. TLC (50% ethyl acetate/CH₂Cl₂)of the reaction indicated the complete conversion of the startingmaterial. The reaction was quenched with solid sodium bicarbonate (500mg) and filtered. The filtrate was evaporated and the oily residue(pinkish) that obtained was purified by silica gel flash chromatographyusing CH₂Cl₂/ethyl acetate (100/0 to 80/20, in 5% increments) as theeluent to obtain the product 103 (80 g, 93.2%).). ¹H NMR (300 MHz,(CDCl₃): δ1.31 (s, 3H), 1.47 (s, 3H), 2.95 (bs, 1H), 3,41 (s, 3H),3.66-3.77 (m, 3H), 4.07 (dd, 1H, J=6.04 & 2.75 Hz), 4.16 (t, 1H, J=6.04& 4.67 Hz), 4.60 (d, 1H, J=2.74 Hz).

Example 81Methyl-4-azido-4-deoxy-2,3-O-isopropylidene-β-D-ribopyranoside (104)

[0235] To a mixture of pyridine (6.4 mL, 79.65 mmol) and dimethylaminopyridine (100 mg, 0.72 mmol) in anhydrous CH₂Cl₂ (400 mL) was slowlyadded trifluoromethanesulfonic anhydride (11.82 mL, 71.68 mmol) at −20°C. The mixture was stirred at −20° C. for 5 min and was then added asolution of 103 (5.0 g, 24.50 mmol) in CH₂Cl₂ (50.0 mL) The reactionmixture was stirred at −20° C. for 15 min. It was then poured into amixture of ice-water (500 mL) and the organic layer separated. Theaqueous phase was extracted with CH₂Cl₂ (2×100 mL). The combined organiclayer was washed with brine (500 mL), dried (NaSO₄) and evaporated toobtain the product as pale yellow gummy solid (14 g).

[0236] To a solution of abovemethyl-4O-trifluoromethenesulfonyl-2,3-O-isopropylidine-β-L-lyxopyranosidein a mixture of DMF (350 mL) and tetramethyl urea (50 mL) was addedsodium azide (30.0 g, 461.53 mmol, 18.83 eq) at 0-5° C. (ice-water bath)and stirred at 23° C. for 3 h. The volatiles were evaporated and theresidue was diluted with CH₂Cl₂ (500 mL) and water (200 mL). The organiclayer was separated and washed with water (2×250 mL) and brine (300 mL),dried (NaSO₄) and evaporated to obtain an oily residue which waspurified by flash silica gel chromatography using hexane/ethyl acetate(100/0; 97.5/2.5; and 95/5) as the eluent to obtain the product 104 (2.8g, 49.88% for the two steps). ¹H NMR (300 MHz, (CDCl₃): δ1.36 (s, 3H,CH₃), 1.54 (s, 3H, CH₃), 3.42 (s, 3H, OCH₃), 3.7-3.9 (m, 3H), 4.01 (dd,1H, J=6.05 & 3.85 Hz), 4.48 (d, 1H, J=3.85 Hz), 4.51 (m, 1H).

Example 82N-Acetyl-4-amino-4-deoxy-2,3-O-isopropylidene-β-D-methyl-ribopyranoside(105)

[0237] To a solution of 104 (6.5 g, 28.38 mmol) in MeOH (50.0 mL) wasadded NaHCO₃ (2.38 g, 28.38 mmol) followed by Pd/C (5% w/w, 650 mg). Thereaction mixture was shaken well under H₂ (40 psi) atmosphere at roomtemperature for 1 h. The TLC (30% ethyl acetate/hexane) indicatedcompletion of the reaction. The reaction mixture was filtered overcelite bed and the filtrate was evaporated to dryness. The residue wasco-evaporated with toluene (2×20 mL) and pyridine (2×20 mL). Theresulting residue was then carried forward to the next reaction withoutfurther purification.

[0238] To a mixture of the above residue (5.76 g, crude from the abovereaction) and DMAP (0.059 g, 0.425 mmol) in pyridine (6.8 mL, 84.5 mmol)was added acetic anhydride (4.01 mL, 42.57 mmol) at 0° C. The reactionmixture was stirred at room temperature for 2 h. The TLC (100% ethylacetate) indicated completion of the reaction. MeOH (1.0 mL) was addedand the volatiles were evaporated. The residue was dissolved in CH₂Cl₂(300 mL) and this solution was then washed with cold and dil. HCl (0.5M,3×200 mL), sat. NaHCO₃ (200 mL) and brine (200 mL), dried (Na₂SO₄) andevaporated. The residue that obtained was purified by flashchromatography over silica gel using ethyl acetate/hexane (0/100 to10/90 to 20/80 to 50/50 to 100/0) as the eluent to obtain the product105 (in a combined yield of 3.76 g, 54.11%). ¹H NMR (300 MHz, (CDCl₃):δ1.35 (s, 3H, CH₃), 1.51 (s, 3H, CH₃), 2.0 (s, 3H, COCH₃), 3.37 (t, 1H),3.45 (s, 3H, OCH₃), 3.85 (dd, 1H), 4.05 (dd, 1H), 4.38 (dd, 1H), 4.40(d, 1H, J=4.5 Hz), 4.58 (m, 1H), 5.78 (bd, 1H).

Example 83 1,2,3,5-Tetra-O-acetyl-4-deoxy-4-(acetamido)-D-ribofuranose(106)

[0239] A solution of 105 (5.0 g, 20.40 mmol) in a mixture of distilledwater and AcOH (1:1, 50 mL) was heated at 70-75° C. for 1.5 h. The TLC(100% ethyl acetate) indicated completion of the reaction. Absolute EtOH(2×30 mL) was added and co-evaporated the volatiles to obtain a drysolid residue. To this solid was added a mixture of glacial acetic acidand acetic anhydride (50 mL, 1:1) and cooled to 0° C., and treated withconc. H₂SO₄ (1.5 mL). The reaction mixture was stirred at 0° C. for 30min and then kept at 4° C. for 2 days. The reaction mixture was treatedwith anhy. NaOAc (15.0 g) and stirred at roo temperature for 30 min. Thereaction mixture was then poured into ice-water mixture (300 mL) andextracted with CH₂Cl₂ ((2×250 mL). The combined organic layer was wishedwith water (2×250 mL) and brine (400 mL), dried (Na₂SO₄) and evaporated.The crude residue that obtained was purified by flash chromatographyover silica gel using MeOH/CH₂Cl₂ (0/100 to 3/97) as the eluent to givepure product 106 (3.71 g, 50.82%). ¹H NMR (300 MHz, (CDCl₃): δ1.99-2.11(m, 15H, 5xCH₃), 4.17-4.5 (m, 3H), 5.27-5.52 (m, 2H), 6.35 (s, 0.75H),6.53 (d, 0.25H, J=4.8 Hz).

Example 84Methyl-1-(2′,3′,5′-tri-O-acetyl-4′-deoxy-4′-acetamido-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxylate(107)

[0240] A suspension of methyl-1,2,4-triazole-3-carboxylate (1.77 g,13.97 mmol) and ammonium sulphate (177 mg) in hexamethyldisilazane (40mL) was refluxed for 2.5 h under N₂ atmosphere. The reaction mixture wasevaporated to dryness and the residue was suspended in1,2-dichloroethane (50 mL). It was then treated with a solution of 106(4.4 g, 12.25 mmol) in 1,2-dichloroethane (50 mL). To the reactionmixture was then added fuming SnCl₄ (1.63 mL, 13.97 mmol) at 0-5° C.(ice-water bath) and stirred at room temperature for 1 h. The reactionmixture was carefully quenched with saturated solution of NaHCO₃ (50 mL)and then diluted with CH₂Cl₂ (200 mL). The mixture was filtered over acelite bed (5 g) and washed with CH₂Cl₂ (100 mL). The organic layer ofthe filtrate was separated and the aqueous layer was extracted withCH₂Cl₂ (2×100 mL). The combined organic layer was washed with water(2×300 mL) and brine (500 mL), dried (Na₂SO₄) and evaporated. The cruderesidue that obtained was recrystallized from ethyl acetate (40 mL) toobtain pure titled product 107 (2.7 g, 51.71%). ¹H NMR (300 MHz,(CDCl₃): δ2.03-2.15 (m, 12H, 4xCOCH₃), 3.95 (s, 3H, OCH₃), 4.2 (m, 1H,H_(5′)), 4.43 (m, 2H, H_(4′) & H_(5′)), 5.65 (dd, 1H, H_(3′), J=4.67 &1.1 Hz), 6.17 (t, 1H, H_(2′), J=4.67 & 6.04 Hz), 6.28 (d, 1H, H_(1′),J=6.04 Hz), 8.47 (s, 0.86H, major rotamer, C₅H), 8.60 (s, 0.14H, minorrotamer, C₅H). Anal. Calcd. for C₁₇H₂₂N₄O₉: C, 47.89; H, 5.20; N. 13.14.Found: C, 47.93; H, 5.40; N, 13.27.

Example 851-(4′-Deoxy-4′-acetamido-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide(108)

[0241] A solution of 107 (2.7 g, 6.33 mmol) in saturated methanolicammonia (100 mL) was stirred at room temperature in steel bomb for 16 h.The reaction mixture was evaporated to dryness and the residue thatobtained was purified by flash chromatography over alumina using thesolvent mixture ethyl acetate/n-propyl alcohol/water (64/4/32 to57/14/29%, lower layer) as the eluent to afford the titled product 108(1.7 g). The product was wet −5% with ethyl alcohol and alsocontaminated little acetamide. ¹H NMR (300 MHz, CD₃OD): δ1.87 (s, 0.86H,COCH₃, minor rotamer (min)), 2.14 (s, 2.14H, COCH₃, major rotamer(maj)), 3.87 (d, 2H, H_(5′), J=6.59 Hz), 4.1-4.01 (m, 1H, H_(4′)), 4.26(d, 0.75H, J=4.12 Hz, H_(3′), maj), 4.31 (t, 0.25H, J=3.8 Hz, H_(3′),min), 4.54 (t, 0.25H, J=4.1 Hz, H_(2′), min), 4.85 (dd, 0.75H, J=4.4 &6.05 Hz, H_(2′), maj), 6.03 (d, 0.75H, J=6.04 Hz, H_(1′), maj), 6.81 (d,0.25H, J=4.13 Hz, H_(1′), min), 8.69 (s, 0.75H, C₅H, maj), 8.95 (s,0.25H, C₅H, min), Anal. Calcd. for C₁₀H₁₅N₅O₅: C, 42.10; H, 5.30; N,24.55. Found: C, 42.21; H, 5.19; N, 24.23.

Example 861-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide(109)

[0242] A solution of 108 (0.7 g, 2.45 mmol) in pyridine (15 mL) wastreated with 1,3-dichloro-1,1,3,3-tetraisopropyl-disiloxane (1.06 mL,3.31 mmol) and stirred at room temperature for 16 h. The reactionmixture was carefully quenched with saturated solution of NaHCO₃ (5 mL)and diluted with CH₂Cl₂ (100 mL). The organic layer was separated andthe aqueous layer was extracted with CH₂Cl₂ (2×25 mL). The combinedorganic layer was washed with water (2×100 mL) and brine (100 mL), dried(Na₂SO₄) and evaporated. The crude residue was purified by flashchromatography over silica gel using CHCl₃/MeOH (100/0-98/2-95/5-90/10)as the eluent to afford 109 (0.7 g, 54%). ¹H NMR (300 MHz, CDCl₃):δ0.93-1.18 (m, 24H), 1.38 (m, 2H), 2.02 (s, 0.84H, COCH₃, minor rotamer(min)), 2.15 (s, 2.16H, COCH₃, major rotamer (maj)), 3.83 (m, 1H,H_(5′)), 3.98-4.13 (m, 1H, H_(5′)), 4.33 (d, 0.34H, J=3.85 Hz, H_(2′),min), 4.42 (d, 0.66H, J=4.67 Hz, H_(2′), maj), 4.52 (dd, 0.34H, H_(4′),min), 4.65 (dd, 0.66H, H₄ ′, maj), 5.29 (t, 1H, J=4.97 Hz, H_(3′)), 5.80(bs, 0.66H, maj), 5.94 (bs, 0.34H, min), 5.99 (s, 0.34H, H_(1′), min),6.40 (s, 0.66H, H_(1′), maj), 6.91 (bs, 0.66H, maj), 7.01 (bs, 0.34H,min), 8.37 (s, 0.66H, C₅H, maj), 8.53 (s, 0.34H, C₅H, min).

Example 871-[2′-O-(p-Tolylthionoformyl)-3′,5′-O-(1,1,3,3-tetraisopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide(110)

[0243] To a solution of 109 (0.6 g, 1.138 mmol) in a mixture of CH₂Cl₂(9 mL) and pyridine (1 mL) was added O-(p-tolyl)thionochloroformate(0.219 mL, 1.42 mmol) and the reaction mixture was stirred at roomtemperature for 16 h. The reaction mixture was quenched with saturatedsolution of NaHCO₃ (5 mL) and diluted with CH₂Cl₂ (100 mL). The organiclayer was separated and the aqueous layer was extracted with CH₂Cl₂(2×25 mL). The combined organic layer was washed with water (2×100 mL)and brine (100 mL), dried (Na₂SO₄) and evaporated. The crude residue waspurified by flash chromatography over silica gel using CHCl₃/ethylacetate (100/0-95/5-90/10) as the eluent to afford pure product 110(0.35 g, 45%). ¹H NMR (300 MHz, CDCl₃): δ1.04-1.15 (m, 24H), 1.32 (m,2H), 2.01 (s, 1H, COCH₃, minor rotamer (min)), 2.19 (s, 2H, COCH₃, majorrotamer (maj)), 2.35 (s, 3H, CH₃), 3.92 (m, 1H, H_(5′)), 4.05 (m, 1H,H_(5′)), 4.68-4.81 (m, 1H, H_(4′)), 5.5 (t, 1H, J=6.05 & 5.22 Hz,H_(3′)), 5.75 (bs, 0.66H, maj), 5.88 (bs, 0.34H, min), 6.10 (d, 1H,J=4.67 Hz, H_(2′)), 6.17 (s, 0.34H, H_(1′), min), 6.54 (s, 0.66H,H_(1′), maj), 6.87 (bs, 0.66H, maj), 6.96 (d, 2H, J=8.24 Hz,aromatic-H), 6.98 (bs, 0.34H, min), (7.20 (d, 2H, J=8.24 Hz), 8.40 (s,0.66H, C₅H, maj), 8.68 (s, 0.34H, C₅H, min).

Example 881-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-2′,4′-dideoxy-4′-acetamido-β-D-ribofuranosyl]-1,2,4-triazole-3-carboxamide(111)

[0244] A solution of 110 (0.35 g, 0.516 mmol) in toluene (20 mL) waspurged with argon for 20 min and then treated with2,2′-azobisisobutyronitrile (0.084 g, 0.516 mmol) and tributyltinhydride (0.274 mL, 1.03 mmol). The reaction mixture was refluxed for 3 hunder a stream of argon. The reaction mixture was evaporated to drynessand the crude residue was purified by flash chromatography over silicagel using CHCl₃/ethyl acetate (100/0-90/10-70/30-40/60-20/80-0/100) asthe eluent to afford the product 111 (0.23 g, 87%). ¹H NMR (300 MHz,CDCl₃): δ0.95-1.15 (m, 24H), 1.24 (m, 2H), 2.0 (s, 0.9H, COCH₃, minorrotamer (min)), 2.13 (s, 2.1H, COCH₃, major rotamer (maj)), 2.36-2.58(m, 1H, H_(2′)), 2.84 (m, 1H, H_(2′)), 3.74-3.92 (m, 2H, H_(5′)), 4.11(m, 0.66H, H_(4′), maj), 4.49-4.67 (m, 0.34H, H_(4′), min), 5.3 (m, 1H,H_(3′)), 5.88 (bs, 0.66H, maj), 6.01 (bs, 0.34H, min), 6.14 (d, 0.34H,J=6.02 Hz, H_(1′), min), 6.54 (d, 0.66H, J=7.97 Hz, H_(1′), maj), 6.89(bs, 0.66H, maj), 7.03 (bs, 0.34H, min), 8.35 (s, 0.66H, C₅H, maj), 8.55(s, 0.34H, C₅H, min).

Example 891-(2′,4′-Dideoxy-4′-acetamido-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide(112)

[0245] A solution of 111 (0.23 g, 0.45 mmol) in CH₂Cl₂ (5 mL) wastreated with triethylamine trishydrofluride (0.29 mL, 1.79 mmol) at roomtemperature. The reaction mixture was stirred for 48 h at roomtemperature. The volatiles were removed and the residue was purified byflash chromatography over silica gel using CHCl₃/MeOH (100/0-95/5-90/10)as the eluent to afford pure product 112 (0.08 g, 66%). ¹H NMR (300 MHz,CD₃OD): 67 1.95 (s, 0.36H, COCH₃, minor rotamer (min)), 2.16 (s, 2.64H,CH₃, major rotamer (maj)), 2.51 (m, 1H, H_(2′)), 2.87 (m, 1H, H_(2′)),3.82 (m, 2H, H_(5′)), 3.99 (t, 1H, J=6.87 Hz, H_(4′)), 4.44 (d, 1H,J=4.12 Hz, H_(3′)), 6.54 (t, 1H, J=7.69 Hz, H_(1′)), 8.63 (s, 0.88H,C₅H, maj), 8.88 (s, 0.12H, C₅H, min). Anal. Calcd. for C₁₀H₁₅N₅O₄: C,44.60; H, 5.62; N, 26.01. Found: C, 44.71; H, 5.69; N, 25.98.

Example 90 Methyl-2,3-O-isopropylidene-α-D-lyxopyranoside (115)

[0246] To a methanolic HCl solution [500 mL, 0.5% w/v, prepared in situby reaction of acetyl chloride (5 mL, 70.37 mmol) with MeOH(Fisher HPLCgrade)] was added D-lyxose (113, 100 g, 666.66 mmol) and refluxed for 5h under N₂ atmosphere. The reaction mixture was neutralized withpre-treated¹ amberlite basic resin IRA-410 (100.0 g) for 10 min understirring. The resin was filtered and washed with methanol (3×125 mL).The combined washings were evaporated to obtain a color less syrup ofmethyl-β-D-lyxopyranoside (114, 110 g, a quantitative yield) which wascarried forward for the next reaction without further purification

[0247] Note:

[0248] Preparation of pre-treated Amberlite Resin IRA-410: The resin(100 g) was treated with aq. NaOH (0.5M, 200 mL) for 15 min. Understirring and filtered and washed with deionized water (4×300 mL) untilthe pH of washings showed neutral to pH paper. Finally the resin waswashed with anhydrous MeOH (3×30 mL) and used immediately.

[0249] To a suspension of 114 (110 g, 666.66 mmol) in a mixture of2,2-dimethoxy propane (400.0 mL) and anhydrous acetone (400.0 mL) wasadded a solution (4M) of HCl in dioxane (8.0 mL) and the reactionmixture was stirred at 25° C. for 16 h. The TLC (50% ethylacetate/CH₂Cl₂) indicated completion of the reaction. The reaction wasquenched with solid sodium bicarbonate (500 mg) and filtered. Thefiltrate was evaporated and the oily residue (pinkish) was purified bysilica gel flash chromatography using CH₂Cl₂/ethyl acetate (100/0 to80/20, with 5% increments) as the eluent to obtain 115 (63.97%, 87 g,overall yield for both the steps).

Example 91Methyl-4-azido-4-deoxy-2,3-O-isopropylidene-β-L-ribopyranoside(116)

[0250] To a mixture of pyridine (6.432 mL, 79.9 mmol) and dimethylaminopyridine (105 mg, 0.75 mmol) in anhydrous CH₂Cl₂ (600 mL) was slowlyadded trifluoromethanesulfonic anhydride (10.72 mL, 65 mmol) at −20° C.The mixture was stirred at −20° C. for 5 min and then added a solutionof 115 (10.2 g, 50 mmol) in CH₂Cl₂ (100.0 mL), and the reaction mixturestirred at −20° C. for 15 min. The TLC (15% ethyl acetate/hexane)indicated completion of the reaction. The reaction mixture was pouredinto a mixture of ice-water (500 mL) and the organic layer wasseparated. The aqueous phase was extracted with CH₂Cl₂ (2×100 mL). Thecombined organic layer was washed with water (2×250 mL) and brine (500mL), dried (NaSO₄) and evaporated to obtain the intermediate triflateproduct as a pale yellow gummy solid (16 g).

[0251] To a solution of abovemethyl-4-O-trifluoromethanesulfonyl-2,3-O-isopropylidene-β-D-lyxopyranoside(16 g) in DMF (300 mL) was cooled to 0° C. Lithium azide (12.5 g, 255.6mmol) was added and stirred at 23° C. for 3 h. The reaction mixture wasdiluted with toluene (200 mL) and the volatiles were evaporated. Theresidue was dissolved in a mixture of CH₂Cl₂ (500 mL) and water (200mL). The organic layer was separated and washed with water (2×250 mL),brine (300 mL), dried (NaSO₄) and evaporated to obtain an oily residuewhich upon purification by flash silica gel chromatography usinghexane/ethyl acetate (100/0; 97.5/2.5; and 95/5) as the eluent affordedpure azido product 116 (5.74 g, 50.2%). ¹H NMR (300 MHz, (CDCl₃): δ1.38(s, 3H, CH₃), 1.55 (s, 3H, CH₃), 3.44 (s, 3H, OCH₃), 3.7-3.9 (m, 3H),4.03 (dd, 1H, J=6.32 & 3.85 Hz), 4.49 (d, 1H, J=3.84 Hz), 4.52 (m, 1H).

Example 92N-Acetyl-4-amino-4-deoxy-2,3-O-isopropylidene-β-L-methyl-ribopyranoside(117)

[0252] To a solution of 116 (12.1 g, 52.83 mmol) in MeOH (40.0 mL) wasadded Pd/C (5% w/w, 1.2 g) and the reaction mixture was shaken wellunder H₂ (50 psi) atmosphere at room temperature for 1 h. The TLC (30%ethyl acetate/hexane) indicated completion of the reaction. The reactionmixture was filtered over celite bed and the filtrate evaporated todryness, and co-evaporated with toluene (2×50 mL) and pyridine (2×25mL). This residue was then carried forward for the next reaction withoutfurther purification.

[0253] To the above crude mixture was added DMAP (0.7 g, 5.0 mmol),pyridine (25.0 mL, 310.55 mmol) in CH₂Cl₂ (250.0 mL) followed by aceticanhydride (25.0 mL, 265.0 mmol) at −5° C. (ice-acetone bath). After theaddition, the cooling bath was removed and the reaction mixture wasstirred for 16 h. The TLC (100% ethyl acetate) indicated completion ofthe reaction. MeOH (10.0 mL) was added and the volatiles wereevaporated. The residue was dissolved in CH₂Cl₂ (300 mL) and thissolution was then washed with water (2×200 mL) and brine (200 mL), dried(Na₂SO₄) and evaporated. The residue was purified by flashchromatography using ethyl acetate/hexane (from 5/95 to 20/80 to 60/40to 80/20) as the eluent to obtain the product 117 (in a combined yieldof 11.49 g, 88.83%). ¹H NMR (300 MHz, (CDCl₃): δ1.34 (s, 3H, CH₃), 1.51(s, 3H, CH₃), 1.99 (s, 3H, COCH₃), 3.37 (t, 1H), 3.83 (dd, 1H, J=5.77 &3.49 Hz), 4.01 (t, 1H, J=5.77 & 4.67 Hz), 4.35 (t, 1H, J=5.5 & 4.67 Hz),4.40 (d, 1H, J=4.4 Hz), 4.54 (m, 1H), 5.76 (bd, 1H, J=7.97 Hz),.

Example 93 1,2,3,5-Tetra-O-acetyl-4-deoxy-4-(acetamido)-L-ribofuranose(118)

[0254] A solution of 117 (8.9 g) in a mixture of distilled water andAcOH (1:1, 100 mL) was heated at 70-75° C. for 1.5 h. TLC (100% ethylacetate) indicated completion of the reaction. Absolute EtOH (2×50 mL)was added and co-evaporated to obtain a dry solid residue. To this solidwas added a mixture of glacial acetic acid and acetic anhydride (100.0mL, 1:1) and cooled to 0° C. (ice-water bath), and treated with conc.H₂SO₄ (1.0 mL). The reaction mixture was stirred at 0° C. for 30 min andthen kept at 4° C. for 2 days. The reaction mixture was treated withanhydrous NaOAc (10.0 g) and stirred at room temperature for 30 min. Thereaction mixture was then poured into ice-water mixture (400 mL) andextracted with CH₂Cl₂ ((2×250 mL). The combined organic layer was washedwith water (2×500 mL) and brine (400 mL), dried (Na₂SO₄) and evaporated.The crude product that obtained was purified by flash chromatographyusing ethyl acetate/hexane (25/75 to 50/50) as the eluent to obtain 118(6.6 g, 50.67%). ¹H NMR (300 MHz, (CDCl₃): δ2.0-2.12 (m, 15H, 5×COCH₃),4.18-4.51 (m, 3H), 5.33-5.36 (m, 1H), 5.45-5.55 (m, 1H), 6.36 (s,0.75H), 6.55 (d, 0.25H, J=5.22 Hz).

Example 94Methyl-1-(2′,3′,5′-triacetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)-1,2,4-triazole-3-carboxylate(119)

[0255] A suspension of methyl-1,2,4-triazole-3-carboxylate (1.022 g,8.05 mmol) and ammonium sulphate (100 mg) in hexamethyldisilazane (20mL) was refluxed for 2.5 h under N₂ atmosphere. The volatiles wereevaporated and the residue was suspended in 1,2-dichloroethane (50 mL).It was then treated with a solution of 118 (2.513 g, 7 mmol) in1,2-dichloroethane (50 mL). To the reaction mixture was then addedfuming SnCl₄ (0.94 mL, 8.05 mmol) at 0-5° C. (ice-water bath). Thereaction mixture was stirred at room temperature for 1 h. The reactionwas carefully quenched with saturated solution of NaHCO₃ (50 mL) anddiluted with CH₂Cl₂ (200 mL). The mixture was filtered over a celite bed(5 g) and washed with CH₂Cl₂ (100 mL). The organic layer of the filtratewas separated and the aqueous layer was extracted with CH₂Cl₂ (2×100mL). The combined organic layer was washed with water (2×300 mL) andbrine (500 mL), dried (Na₂SO₄) and evaporated. The crude residue wascrystallized from ethyl acetate (40 mL) to obtain pure titled product119 (1.8 g, 60.36%). ¹H NMR (300 MHz, (CDCl₃): δ2.03-2.14 (m, 12H,4×COCH₃), 3.93 (s, 3H, OCH₃), 4.2 (m, 1H, H_(5′)), 4.41 (m, 2H, H_(4′)&H_(5′)), 5.64 (d, 1H, H_(3′), J=4.67 Hz), 6.16 (t, 1H, H_(2′), J=4.95 &5.77 Hz), 6.27 (d, 1H, H_(1′), J=6.05 Hz), 8.46 (s, 0.86H, majorrotamer, C₅H), 8.60 (s, 0.14H, minor rotamer, C₅H). Anal. Calcd. forC₁₇H₂₂N₄O₉: C, 47.89; H, 5.20; N. 13.14. Found: C, 47.77; H, 5.49; N,13.04.

Example 951-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)-1,2,4-triazole-3-carboxamide(120)

[0256] A solution of 119 (3.26 g, 7.65 mmol) in saturated methanolicammonia (100 mL) was stirred at room temperature for 16 h. The reactionwas evaporated to dryness and the residue was purified by flashchromatography over alumina using the solvent mixture ethylacetate/n-propyl alcohol/water (lower layer, 64/4/32 to 57/14/29%) toafford the titled product 120 (1.7 g, 77.98%). ¹H NMR (300 MHz,(DMSO-d₆+D₂O): δ1.64 (s, 0.75H, COCH₃, minor rotamer (min)), 2.0 (s,2.25H, COCH₃ major rotamer (maj)), 3.84-3.54 (m, 3H, H-_(4′)& H-_(5′)),4.1 (m, 1H, H-_(3′)), 4.32 (t, 0.25H, J=4.4 Hz, H-_(2′), min), 4.56 (t,0.75H, J=4.2 Hz, H-_(2′), maj), 5.82 (d, 0.75H, J=6.32 Hz, H-_(1′),maj), 6.01 (d, 0.25H, J=4.4 Hz, H-_(1′), min), 8.74 (s, 0.75H, C₅H,maj), 8.96 (s, 0.25H, C₅H, min).). Anal. Calcd. for C₁₀H₁₅N₅O₅: C,42.10; H, 5.30; N. 24.55. Found: C, 42.44; H, 5.49; N, 24.69.

Example 961-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-L-ribofuranosyl]-1,2,4-triazole-3-carboxamide(121)

[0257] A suspension of 120 (0.75 g, 2.63 mmol) in pyridine (15 mL) wastreated with 1,3-dichloro-1,1,3,3-tetraisopropyl-disiloxane (1.09 mL,3.42 mmol) and stirred at room temperature for 16 h. The reactionmixture was carefully quenched with saturated solution of NaHCO₃ (5 mL)and diluted with CH₂Cl₂ (100 mL). The organic layer was separated andthe aqueous layer was extracted with CH₂Cl₂ (2×25 mL). The combinedorganic layer was washed with water (2×100 mL) and brine (100 mL), dried(Na₂SO₄) and evaporated. The crude residue that obtaine was purified byflash chromatography over silica gel using CHCl₃/MeOH(100/0-98/2-95/5-90/10) as the eluent to afford the product 121 (0.75 g,54%). ¹H NMR (300 MHz, CDCl₃): δ0.93-1.17 (m, 24H), 1.37 (m, 2H), 2.01(s, 1H, COCH₃, minor rotamer (min)), 2.14 (s, 2H, COCH₃, major rotamer(maj)), 2.98 (s, 0.34H, OH, exchangeable, min), 3.34 (s, 0.66H, OH,exchangeable, maj), 3.78-3.84 (m, 1H, H_(5′)), 3.97-4.14 (m, 2H, H_(4′)& H_(5′)), 4.33 (d, 0.34H, J=4.12 Hz, H_(2′), min), 4.41 (d, 0.66H.J=4.95 Hz, H_(2′), maj), 4.52 (m, H_(4′), min), 4.65 (m, H_(3′), min),5.28 (t, J=4.95 Hz, H_(3′), maj), 5.80 (s, 0.66H, exchangeable, maj),5.95 (s, 0.34H, exchangeable, min), 5.97 (s, 0.34H, H_(1′), min), 6.39(s, 0.66H, H_(1′), maj), 6.89 (s, 0.66H, exchangeable, maj), 7.00 (s,0.34H, exchangeable, min), 8.37 (s, 0.66H, C₅H, maj), 8.52 (s, 0.34H,C₅H, min).

Example 97 1[2′ O (p Toluoylthionoformyl) 3′,5′ O (1,1,3,3tetraisopropyl 1,3disiloxanediyl)-4′-deoxy-4′-acetamido-β-L-ribofuranosyl]-1,2,4-triazole-3-carboxamide(122).

[0258] To a solution of 121 (0.65 g, 1.23 mmol) in a mixture of CH₂Cl₂(9 mL) and pyridine (1 mL) was added O-(p-tolyl)thionochloroformate(0.285 mL, 1.85 mmol) and the reaction mixture was stirred at roomtemperature for 16 h. The reaction mixture was quenched with saturatedsolution of NaHCO₃ (5 mL) and diluted with CH₂Cl₂ (100 mL). The organiclayer was separated and the aqueous layer was extracted with CH₂Cl₂(2×25 mL). The combined organic layer was washed with water (2×100 mL)and brine (100 mL), dried (Na₂SO₄) and evaporated. The crude residuethat obtained was purified by flash chromatography over silica gel usingCHCl₃/ethyl acetate (100/0-95/5-90/10) as the eluent to afford theproduct 122 (0.33 g, 39.52%). ¹H NMR (300 MHz, CDCl₃): δ0.92-1.15 (m,24H), 2.01 (s, 1H, COCH₃, minor rotamer (min)), 2.19 (s, 2H, COCH₃,major rotamer (maj)), 2.35 (s, 3H, CH₃), 3.92 (m, 1H, H_(5′)), 4.07 (m,2H, H_(4′) & H_(5′)), 4.68-4.8 (m, H_(3′), min), 5.50 (m, H_(3′), maj),5.7 (s, 0.66H, exchangeable, maj), 5.82 (s, 0.34H, exchangeable, min),6.10 (d, 1H, J=4.94 Hz, H_(2′)), 6.17 (s, 0.34H, H_(1′), min), 6.54 (s,0.66H, H_(1′), maj), 6.70 (s, 0.34H, exchangeable, min), 6.86 (s, 0.66H,exchangeable, maj), 6.96 (d, 2H, J=8.52 Hz, aromatic-H), 7.21 (d, 2H,J=8.24 Hz aromatic-H), 8.40 (s, 0.66H, C₅H, maj), 8.69 (s, 0.34H, C₅H,min).

Example 981-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-2′,4′-dideoxy-4′-acetamido-β-L-ribofuranosyl]-1,2,4-triazole-3-carboxamide(123)

[0259] A solution of 122 (0.325 g, 0.48 mmol) in toluene (20 mL) waspurged with argon for 20 min. To the solution were added2,2′-azobisisobutyronitrile (0.078 g, 0.48 mmol) and tributyltin hydride(0.25 mL, 0.96 mmol). The reaction mixture was refluxed for 6 h under astream of argon. The reaction was evaporated to dryness and the cruderesidue was purified by flash chromatography over silica gel usingCHCl₃/ethyl acetate (100/0-90/10-70/30-40/60-20/80-0/100) as the eluentto afford 123 (0.22 g, 89.68%). ¹H NMR (300 MHz, CDCl₃): δ0.92-1.15 (m,24H), 1.28 (m, 2H), 2.0 (s, 0.66H, COCH₃, minor rotamer (min)), 2.13 (s,2.34H, COCH₃, major rotamer (maj)), 2.36-2.58 (m, 1H, H_(2′)), 2.85 (dd,1H, J=13.73 & 7.41 Hz, H_(2′)), 3.74-4.09 (m, 3H, H_(4′) & H_(5′)),4.49-4.67 (m, H_(3′), min), 5.30 (m, H_(3′), maj), 5.83 (s, 0.8H,exchangeable, maj), 5.94 (s, 0.2H, exchangeable, min), 6.14 (d, 0.2H,J=6.05 Hz, H_(1′), min), 6.54 (d, 0.8H, J=8.24 Hz, H_(1′), maj), 6.89(s, 0.8H, exchangeable, maj), 7.04 (s, 0.2H, exchangeable, min), 8.35(s, 0.8H, C₅H, maj), 8.55 (s, 0.2H, C₅H, min).

Example 991-(2′,4′-Dideoxy-4′-acetamido-β-L-ribofuranosyl)-1,2,4-triazole-3-carboxamide(124)

[0260] A solution of 123 (0.2 g, 0.39 mmol) in CH₂Cl₂ (5 mL) was treatedwith triethylamine tris-hydrofluoride (0.25 mL, 1.56 mmol) at roomtemperature. The reaction mixture was stirred for 48 h and the volatileswere evaporated to dryness. The residue was purified by flashchromatography over silica gel using CHCl₃/MeOH (100/0-95/5-90/10-85/15)as the eluent to afford 124 (0.08 g, 66%). ¹H NMR (300 MHz, CD₃OD):δ1.95 (s, 0.36H, COCH₃, minor rotamer (min)), 2.16 (s, 2.64H, COCH₃,major rotamer (maj), 2.51 (m, 1H, H_(2′)), 2.87 (m, 1H, H_(2′)), 3.82(m, 2H, H_(5′)), 3.99 (t, 1H, J=6.87 Hz, H_(4′)), 4.44 (d, 1H, J=4.12Hz, H_(3′)), 6.54 (t, 1H, J=7.69 Hz, H_(1′)), 8.63 (s, 0.88H, C₅H, maj),8.88 (s, 0.12H, C₅H, min). Anal. Calcd. for C₁₀H₁₅N₅O₄: C, 44.60; H,5.62; N, 26.01. Found: C, 44.69; H, 5.71; N, 26.10.

Example 1001-(2′,3′,5′-Tri-O-acetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)thymine(125)

[0261] A suspension of thymine (1.26 g, 10 mmol) and ammonium sulphate(126 mg) in hexamethyldisilazane (25 mL) was refluxed for 5 h under N₂atmosphere. The reaction mixture was evaporated to dryness and theresidue suspended in 1,2-dichloroethane (50 mL). A solution of 118(2.513 g, 7 mmol) in 1,2-dichloroethane (50 mL) was added followed byfuming SnCl₄ (1.17 mL, 10 mmol, 1.42 eq) at 0-5° C. (ice-water bath).The reaction mixture was stirred at room temperature for 1 h. Thereaction mixture was carefully quenched with saturated solution ofNaHCO₃ (50 mL) and diluted with CH₂Cl₂ (200 mL). The mixture wasfiltered over a celite bed (5 g) and washed with CH₂Cl₂ (100 mL). Theorganic layer of the filtrate was separated and the aqueous layer wasextracted with CH₂Cl₂ (2×100 mL). The combined organic layer was washedwith water (2×300 mL) and brine (500 mL), dried (Na₂SO₄) and evaporated.The residue obtained was purified by flash chromatography over silicagel using CHCl₃/acetone (95/5-90/10-85/15-80/20) as the eluent to obtainpure titled product 125 (2.9 g, quantitative). ¹H NMR (300 MHz, CDCl₃):δ1.89-2.2 (m, 15H, 4×COCH₃ & C₅CH₃), 4.08 (m, 0.5H, H_(5′)), 4.37-4.56(m, 2.5H, H_(4′) & H_(5′)), 5.32 (m, 0.5H, H_(3′)), 5.47 (m, 1.5H,H_(2′)& H_(3′)), 6.15 (m, 0.5H, H_(1′)), 6.37 (d, 0.5H, J=6.6 Hz,H_(1′)), 7.16 (s, 0.5H, C₆H), 7.44 (s, 0.5H, C₆H), 9.02 (s, 0.5H, NH,exchangeable), 9.20 (s, 0.5H, NH exchangeable).

Example 101 1-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)thymine (126)

[0262] A solution of 125 (3.1 g, 7.29 mmol) in saturated methanolicammonia (100 mL) was stirred at room temperature in a steel bomb for 16h. The steel bomb was cooled to 0° C., opened and evaporated to dryness.The residue was purified by flash silica gel chromatography over silicagel using CHCl₃/MeOH (95/5-90/10-85/15) as the eluent to afford thetitled product 126 (1.72, 78.86%). ¹H NMR (300 MHz, (DMSO-d₆+D₂O): δ1.70(s, 1.35H, COCH₃, minor rotamer (min)), 1.73 (s, 1.35H, C₅CH₃), 1.77 (s,1.65H, C₅CH₃), 1.98 (s, 1.65H, COCH₃, major rotamer (maj), 3.95-3.57 (m,4H, H_(3′), H_(4′) & H_(5′)), 4.13 (t, 0.55H, , J=4.67 Hz, H_(2′), maj),4.20 (dd, 0.45H, J=4.4 Hz, H_(2′), min), 5.72 (d, 0.45H, J=6.6 Hz,H_(1′), min), 5.88 (d, 0.55H, j=5.77 Hz, H_(1′), maj), 7.68 (s, 0.45H,C₆H, min), 8.00 (s, 0.55H, C₆H, maj). Anal. Calcd. for C₁₂H₁₇N₃O₆: C,48.16; H, 5.73; N, 14.04. Found: C, 48.23; H, 5.81; N, 14.29.

Example 1021-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-L-ribofuranosyl]thymine(127) &1-[(2′,3′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-4′-dideoxy-4′-acetamido-β-L-ribofuranosyl]thymine(128)

[0263] A suspension of 126 (1.72 g, 5.75 mmol) in pyridine (25 mL) wastreated with 1,3-dichloro-1,1,3,3-tetraisopropyl-disiloxane (2.75 mL,8.59 mmol) and stirred at room temperature for 16 h. The reactionmixture was carefully quenched with saturated solution of NaHCO₃ (5 mL)and diluted with CH₂Cl₂ (100 mL). The organic layer was separated andthe aqueous layer was extracted with CH₂Cl₂ (2×25 mL). The combinedorganic layer was washed with water (2×100 mL) and brine (100 mL), dried(Na₂SO₄) and evaporated. The crude residue was purified by flashchromatography over silica gel using hexane/ethyl acetate(90/10-80/20-60/40-20/80-0/100) as the eluent to afford a mixture ofinseparable regio isomeric products 127 & 128 (2.15 g, 69%). ¹H NMR (300MHz, CDCl₃): δ1.0 (m), 1.9-2.13 (m), 3.79-4.13 (m), 4.3-4.47 (m), 4.74(d), 5.07-5.21 (m), 5.47 (s), 5.84 (s), 5.93 (d, J=3.3 Hz), 7.20 (s),7.40(s), 7.53 (s), 7.78 (s), 8.88 (s), 9.13 (s), 9.67 (s).

Example 1031-[2′-O-(p-Tolylthionoformyl)-3′,5′-O-(1,1,3,3-tetrailopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-L-ribofuranosyl]thymine(129) &1-[5′-O-(p-Tolylthionoformyl)-2′,3′-O-(1,1,3,3-tetraisopropyl-1,3-disiloxanediyl)-4′-deoxy-4′-acetamido-β-L-ribofuranosyl]thymine(103)

[0264] To a mixture of 127 and 128 (2 g, 3.69 mmol) in pyridine (20 mL)was added O-(p-toluoyl)thionochloroformate (0.712 mL, 4.43 mmol) and thereaction mixture was stirred at room temperature for 16 h. The reactionmixture was quenched with saturated solution of NaHCO₃ (5 mL) anddiluted with CH₂Cl₂ (100 mL). The organic layer was separated and theaqueous layer was extracted with CH₂Cl₂ (2×25 mL). The combined organiclayer was washed with water (2×100 mL) and brine (100 mL), dried(Na₂SO₄) and evaporated. The crude residue was purified by flashchromatography over silica gel hexane/ethyl acetate(90/10-80/20-70/30-40/60) as the eluent to afford a faster product (0.9g) and a slower product (0.8 g). The combined yield of both the productswas 1.7 g (66.54%). The ¹H NMR analysis of both the products indicatedthat the slower product was 129 while the faster product was 130. 129:¹H NMR (300 MHz, CDCl₃): δ0.98-1.06 (m, 24H), 1.89 (s, 3H, CH₃), 2.00(s, 2H, COCH₃, major rotamer, (maj)), 2.25 (s, 1H, COCH₃, minorrotamer,(min)), 2.34 (s, 3H, CH₃), 3.85-4.03 (m, 2H, H_(5′)), 4.38-4.80(m, 2H, H_(3′) & H_(4′)), 5.3 (m, 0.24H, H_(2′), min), 5.7 (m, 0.76H,H_(2′), maj), 6.01 (s, 1H, H_(1′)), 6.95 (d, 2H, J=8.52 Hz, aromatic-H),7.20 (d, 2H, J=8.52 Hz, aromatic-H), 7.35 (s, 0.24H, C₆H), 7.57 (s,0.76H, C₆H), 8.23 (bs, 0.24H, NH, exchangeable), 8.64 (s, 0.76H, NH,exchangeable). 130: ¹H NMR (300 MHz, CDCl₃): δ1.00-1.06 (m, 26H), 1.87(s, 3H, CH₃), 2.02 (s, 2.4H, COCH₃, major rotamer, (maj)), 2.22 (s,0.6H, COCH₃, minor rotamer, (min)), 4.22-4.5 (m, 3H, H_(4′) & H_(5′))4.88 (m, 1H, H_(3′)), 5.22 (m, 1H, H_(2′)), 6.01 (d, 1H, J=3.02 Hz,H_(1′)), 6.94 (d, 2H, J=8.24 Hz, aromatic-H), 7.21 (d, 2H, J=8.52 Hz,aromatic-H), 7.78 (s, 1H, C₆H), 8.38 (bs, 0.16H, NH, exchangeable, min),8.44 (s, 0.84H, NH, exchangeable, maj).

Example 1041-[(3′,5′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-2′,4′-dideoxy-4′-acetamido-β-L-ribofuranosyl]thymine(131)

[0265] A solution of 129 (0.74 g, 1.070 mmol) in toluene (25 mL) waspurged with argon for 20 min. To this solution was added2,2′-azobisisobutyronitrile (0.174 g, 1.074 mmol) followed bytributyltinhydride (0.56 mL, 2.113 mmol, 2 eq). The reaction mixture wasrefluxed for 6 h under a stream of argon. The volatiles were evaporatedand the crude residue was purified by flash chromatography over silicagel using hexane/ethyl acetate (100/0-90/10-80/20-70/30-60/40) as theeluent to afford 131 (0.45 g, 80.03%). ¹H NMR (300 MHz, CDCl₃):δ0.98-1.06 (m, 24H), 1.26 (m, 2H), 1.90 (s, 3H, CH₃), 1.97 (s, 2.25H,COCH₃, major rotamer, (maj)), 2.17 (s, 0.75H, COCH₃, minor rotamer,(min)), 2.2-2.4 (m, 1.5H, H_(2′)), 2.65 (m, 0.5H, H_(2′)), 3.67 (m, 1H,H_(5′)), 4.0 (m, 1H, H_(5′)) 4.32 (m), 4.64 (m, 1H, H_(4′)), 5.12 (m,1H, H_(3′)), 5.71 (m, 0.15H, H_(1′), min), 6.05 (m, 0.85H, J=6.05 Hz,H_(1′), maj), 7.33 (s, 0.15H, C₆H, min), 7.53 (s, 0.85H, C₆H, maj), 8.23(bs, 0.15H, NH, exchangeable, min), 8.76 (s, 0.85H, NH, exchangeable,maj).

Example 105 1-(2′,4′-Dideoxy-4′-acetamido-β-L-ribofuranosyl)thymine(132)

[0266] A solution of 131 (0.38 g, 0.72 mmol) in CH₂Cl₂ (10 mL) wastreated with triethylamine tris-hydrofluoride (0.585 mL, 3.6 mmol) atroom temperature. The reaction mixture was stirred for 48 h andevaporated to dryness. The residue was purified by flash chromatographyover silica gel using CHCl₃/MeOH (100/0-97/3-94/6-90/10) as the eluentto the titled compound 132 (0.19 g, 92.75%). ¹H NMR (300 MHz, CD₃OD):δ1.83 (s, 1.35H, C₅CH₃), 1.86 (s, 1.65H, C₅CH₃), 1.95 (s, 1.35H, COCH₃,minor rotamer (min)), 2.18 (s, 1.65H, COCH₃, major rotamer (maj)), 2.37(m, 2H, H_(2′)), 4.05-3.73 (m, 3H, H_(4′) & H_(5′)), 4.32 (d, 0.55H,J=3.85 Hz, H_(3′), maj), 4.36 (bs, 0.45H, H_(3′), min), 6.26 (t, 0.45H,J=8.2 Hz, H_(1′), min), 6.49 (t, 0.55H, J=7.4 Hz, H_(1′), maj), 7.70 (s,0.55H, C₆H, maj) 8.18 (s, 0.45H, C₆H, min) Anal. Calcd. forC₁₂H₁₇N₃O₅.½H₂O: C, 49.31; H, 6.21; N, 14.38. Found: C, 49.49; H, 6.43;N, 14.51.

Example 1061-[(2′,3′-O-(1,1,3,3-Tetraisopropyl-1,3-disiloxanediyl)-5′,4′-dideoxy-4′-acetamido-β-L-ribofuranosyl]thymine(133)

[0267] A solution of 130 (1.35 g, 1.954 mmol) in toluene (40 mL) waspurged with argon for 20 min. To this solution was added2,2′-azobisisobutyronitrile (0.32 g, 1.954 mmol) and tributyltinhydride(1.035 mL, 3.905 mmol). The reaction mixture was refluxed for 1.5 hunder a stream of argon. The reaction mixture was evaporated to dryness.The crude residue was purfied by flash chromatography over silica gelusing hexane/ethyl acetate (100/0-90/10-80/20-70/30-60/40) as the eluentto 133 (0.7 g, 68.24%). ¹H NMR (300 MHz, CDCl₃); δ0.98-1.05 (m, 24H),1.24 (m, 2H), 1.46 (d, 1.2H, H_(5′), minor rotamer (min), 1.52 (d, 2.8H,J=6.9 Hz, H_(5′), major rotamer (maj), 1.89 (s, 1.2H, COCH₃, min), 1.93(s, 3H, CH₃), 2.09 (s, 2.8H, COCH₃, maj), 3.86 (m, 0.6H, H_(4′), maj),3.98 (m, 0.4H, H_(4′), min), 4.12-4.36 (m, 1H, H_(3′)), 5.18 (m, 1H,H_(2′)), 5.30 (d, 0.6H, J=6.05 Hz, H_(1′), maj), 5.98 (d, 0.4H, J=3.57Hz, H_(1′), min) 6.99 (s, 0.4H, C₆H, min), 7.08 (s, 0.6H, C₆H, maj),8.53 (bs, 0.6H, NH, exchangeable, maj) 8.66 (bs, 0.4H, NH, exchangeable,min).

Example 107 1-(5′,4′-Dideoxy-4′-acetamido-β-L-ribofuranosyl)thymine(134)

[0268] A solution of 133 (0.6 g, 1.14 mmol) in CH₂Cl₂ (20 mL) wastreated with triethylamine tris-hydrofluoride (0.558 mL, 3.42 mmol) atroom temperature. The reaction mixture was stirred at room temperaturefor 20 h and the volatiles were evaporated to dryness. The residue waspurified by flash chromatography over silica gel using CHCl₃/MeOH(100/0-97/3-94/6-90/10) as the eluent to afford 134 (0.2 g, 61.83%). ¹HNMR (300 MHz, (CD₃OD): δ1.40 (d, 0.36H, J=6.87 Hz, H_(5′), minor rotamer(min)), 1.48 (d, 0.64H, J=6.87 Hz, H_(5′), major rotamer (maj)), 1.87(s, 1.08H, C₅CH₃), 1.91 (s, 1.92H, C₅CH₃) 1.91 (s, 1.08H, COCH₃, min),2.09 (s, 1.92H, COCH₃, maj), 3.84-4.09 (m, 2H, H_(3′) & H_(4′)) 4.33 (m,0.36H, H_(2′), min), 4.67 (m, 0.64H, H_(2′), maj), 5.71 (d, 0.64H,J=6.87 Hz, H_(1′), maj), 6.08 (d, 0.36H, J=5.77 Hz, H_(1′), min), 7.21(s, 0.36H, C₆H, min), 7.27 (s, 0.64H, C₆H, maj). Anal. Calcd. forC₁₂H₁₇N₃O₅: C, 50.88; H, 6.05; N, 14.83. Found: C, 50.91; H, 6.23; N,14.91.

Example 1081-(2′,3′,5′-O-Triacetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)-6-azauracil(135)

[0269] A suspension of 6-azauracil (0.909 g, 8.05 mmol) and ammoniumsulphate (100 mg) in hexamethyldisilazane (20 mL) was refluxed for 2 hunder N₂ atmosphere. The reaction mixture was evaporated to dryness andthe residue was suspended in 1,2-dichloroethane (50 mL). To this stirredsolution was added a solution of 118 (2.513 g, 7 mmol) in1,2-dichloroethane (50 mL) followed by fuming SnCl₄ (0.94 mL, 8.05 mmol,1.15 eq) at 0-5° C. (ice-water bath). The reaction mixture was stirredat room temperature for 16 h. The reaction mixture was carefullyquenched with saturated solution of NaHCO₃ (50 mL) and diluted withCH₂Cl₂ (200 mL). The mixture was filtered over a celite bed (5 g) andwashed with CH₂Cl₂ (100 mL). The organic layer of the filtrate wasseperated and the aqueous layer was extracted with CH₂Cl₂ (2×100 mL).The combined organic layer was washed with water (2×300 mL) and brine(500 mL), dried (Na₂SO₄) and evaporated. The crude residue was purifiedby flash chromatography over silica gel using hexane/ethylacetate(85/15-70/30-50/50-30/70-0/100) as the eluent to obtain the titledproduct 135 (0.5 g, 17%). ¹H NMR (300 MHz, CDCl₃); 2.01-2.15 (m, 12H),4.12-4.48 (m, 3H, H_(4′) & H_(5′)), 5.47 (m, 1H, H_(3′)), 5.57(m, 0.2H,H_(2′), minor rotamer (min)), 5.64 (m, 0.8H, H_(2′), major rotamer(maj)), 6.41 (d, 0.2H, J=5.4 Hz, H_(1′), min), 6.52 (d, 0.8H, J 7.2 Hz,H_(1′), maj), 7.38 (d, 0.6H, J=2.1 Hz, C₅H, maj), 7.54 (s, 0.4H, C₅H,min), 9.22 (bs, 0.6H, NH, exchangeable, maj), 9.46 (bs, 0.4H, NH,exchangeable, min).

Example 1091-(2′,3′,5′-O-Triacetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)-6-carbomethoxyuracil(136)

[0270] A suspension of 6-carbomethoxyuracil (1.7 g, 10 mmol) andammonium sulphate (170 mg) in hexamethyldisilazane (25 mL) was refluxedfor 2 h under N₂ atmosphere. The volatiles were evaporated and theresidue was suspended in 1,2-dichloroethane (50 mL). To this was added asolution of 118 (2.513 g, 7 mmol) in 1,2-dichloroethane (50 mL) followedby fuming SnCl₄ (1.17 mL, 10 mmol, 1.42 eq) at 0-5° C. (ice water bath).The reaction mixture was stirred at room temperature for 16 h. Thereaction mixture was carefully quenched with saturated solution ofNaHCO₃ (50 mL) and diluted with CH₂Cl₂ (200 mL). The mixture wasfiltered over a celite bed (5 g). The organic layer of the filtrate wasseparated and the aqueous layer was extracted with CH₂Cl₂ (2×100 mL).The combined organic layer was washed with water (2×300 mL) and brine(500 mL), dried (Na₂SO₄) and evaporated. The crude residue was purifiedby flash chromatography over silica gel using hexane/ethylacetate(95/5-80/20-70/30-50/50) as the eluent to obtain the titled product 136(2.2 g, 67%). ¹H NMR (300 MHz, CDCl₃): 1.99-2.10 (m, 12H), 3.92 (s, 2H,OCH₃, major rotamer (maj)), 3.98 (s, 1H, OCH₃, minor rotamer (min)),4.00-4.07 (m, 1H, H_(5′)), 4.53 (m, 2H, H_(4′) & H_(5′)), 5.48 (d, 0.8H,J=4.67 Hz, H_(3′), maj), 5.53 (d, 0.2H, J=4.94 Hz, H_(3′), min), 6.13(m, 0.2H, H_(2′), min), 6.20 (dd, 0.8H, J=4.67 & 7.96 Hz, H_(2′), maj),6.30 (s, 0.8H, H_(1′), maj), 6.37 (s, 0.2H, H_(1′), min), 6.58 (d, 0.2H,J=6.87 Hz, C₅H, min), 6.68 (d, 0.8H, J=7.99 Hz, C₅H, maj), 8.70 (bs,0.8H, NH, exchangeable maj), 8.89 (bs, 0.2H, NH, exchangeable, min).

Example 1101-(2′,3′,5′-O-Triacetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)-5-fluorouracil(137)

[0271] A suspension of 5-fluorouracil (1.3 g, 10 mmol) and ammoniumsulphate (130 mg) in hexamethyldisilazane (25 mL) was refluxed for 4 hunder N₂ atmosphere. The reaction mixture was evaporated to dryness andthe residue was suspended in 1,2-dichloroethane (50 mL). The solutionwas then treated with a solution of 118 (2.513 g, 7 mmol) in1,2-dichloroethane (50 mL) followed by fuming SnCl₄ (1.17 mL, 10 mmol,1.42 eq) at 0-5° C. (ice-water bath). The reaction mixture was stirredat room temperature for 16 h. The reaction mixture was carefullyquenched with saturated solution of NaHCO₃ (50 mL) and diluted withCH₂Cl₂ (200 mL). The mixture was filtered over a celite bed (5 g). Theorganic layer of the filtrate was seperated and the aqueous layer wasextracted with CH₂Cl₂ (2×100 mL). The combined organic layer was washedwith water (2×100 mL) and brine (500 mL), dried (Na₂SO₄) and evaporated.The crude residue was purified by flash chromatography over silica gelusing CHCl₃/acetone (80/20) as the eluent to provide pure product 137 (1g, 33.30%). ¹H NMR (300 MHz, CDCl₃ ): 2.02-2.21 (m, 12H), 4.10 (m, 0.5H,H_(5′)), 4.43-4.56 (m, 2.5H, H_(4′) & H_(5′)), 5.30 (m, 0.5H, H_(3′)),5.43-5.54 (m, 1.5H, H_(2′) & H_(3′)), 6.09 (t, 0.5H, J=6.32 & 4.94 Hz,H_(1′)), 6.28 (d, 0.5H, J=4.94 Hz, H_(1′)), 7.48 (d, 0.5H, J=5.77 Hz,C₆H), 7.95 (d, 0.5H, J=5.77 Hz, C₆H), 9.19 (bs, 0.5H, NH, exchangeable),9.34 (bs; 0.5H, NH, exchangeable).

Example 1111-(2′,3′,5′-O-Triacetyl-4′-deoxy-4′-acetamido-β-L-ribofuranosyl)-5-fluorocytosine(138)

[0272] A suspension of 5-fluorocytosine (1.29 g, 10 mmol, 1.42 eq) andammonium sulphate (322 mg) in hexamethyldisilazane (40 mL) was refluxedfor 4 h under N₂ atmosphere. The volatiles were evaporated and theresidue was suspended in 1,2-dichlorothane (50 mL). To this stirredsolution was added a solution of 118 (2.513 g, 7 mmol) in1,2-dichloroethane (50 mL) followed by fuming SnCl₄ (1.17 mL, 10 mmol,1.42 eq) at 0-5° C. (ice-water bath). The reaction mixture was stirredat room temperature for 16 h. The reaction mixture was carefullyquenched with saturated solution of NaHCO₃ (50 mL) and diluted withCH₂Cl₂ (200 mL). The mixture was filtered over a celite bed (5 g). Theorganic layer of the filtrate was seperated and the aqueous layer wasextracted with CH₂Cl₂ (2×100 mL). The combined organic layer was washedwith water (2×300 mL) and brine (500 mL), dried (Na₂SO₄) and evaporated.The crude residue was purified by flash chromatography over silica gelusing CHCl₃/acetone (80/20) to obtain pure product 138 (1 g, 33.55%). ¹HNMR (300 MHz, CDCl₃): 1.98-2.18 (m, 12H), 4.08 (m, 0.5H, H_(5═)),4.37-4.61 (m, 2.5H, H_(4′) & H_(5′)), 5.28 (m, 1H, H_(3′)), 5.44 (t,0.8H, J=4.67 Hz, H_(2′), major rotamer (maj)), 5.55 (d, 0.2H, J=4.39 Hz,H_(2′), major rotamer (min)), 5.76 (bs, 1H, NH₂, exchangeable), 6.27(bt, 0.23H, H_(1′), min), 6.37 (d, 0.77H, J=3.57 Hz, H_(1′), maj), 7.49(d, 0.23H, J=5.77 Hz, C₆H, min), 7.79 (bs, 1H, NH₂ exchangeable), 7.94(d, 0.77H, J=6.32 Hz, C₂H, maj).

Example 112 1-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)-6-azauracil(139)

[0273] A solution of 135 (0.45 g, 1.09 mmol) in saturated methanolicammonia (10 mL) was stirred in a steel bomb at room temperature for 16h. The steel bomb was cooled, opened and evaporated to dryness. Theresidue was purified by flash chromoatography over silica gel usingCHCl₃/MeOH (95/5-90/10-85/15) as the eluent to afford the titld product139 (0.18 g, 57.62%). ¹H NMR (300 MHz, DMSO-d₆): δ1.84 (s, 1.35H, COCH₃,minor rotamer (min)), 1.95 (s, 1.65H, COCH₃, major rotamer (maj)),3.46-3.85 (m, 3H, H_(4′) & H_(5′)), 4.01 (m, 1H, H-_(3′)), 4.22 (m, 1H,H_(2′)), 4.89 (m, 0.45H, OH, min, exchangeable), 5.01 (m, 0.55H, OH,maj, exchangeable),), 5.15 (s, 0.45H, OH, min, exchangeable), 5.28 (s,0.55H, OH, maj, exchangeable), 5.39 (d, 0.45H, J=6.86 Hz, OH, min,exchangeable), 5.50 (d, 0.55H, J=5.7 Hz, OH, maj, exchangeable), 6.0 (d,0.45H, J=7.15 Hz, H_(1′), min), 6.05 (d, 0.55H, J=5.5 Hz, H_(1′), maj),7.50 (s, 0.45H, C₅H, min), 7.61 (s, 0.55H, C₅H, maj), 12.2 (bs, 1H, NH,exchangeable). Anal. Calcd. for C₁₀H₁₄N₄O₆: C, 41.96; H, 4.93; N, 19.57.Found: C, 42.03; H, 5.11; N, 19.64.

Example 1131-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)uracil-6-carboxamide (140)

[0274] A solution of 136 (2 g, 4.26 mmol) in saturated methanolicammonia (20 mL) was stirred at room temperature in a steel bomb for 16h. The steel bomb was cooled, opened and evaporated to dryness. Theresidue that obtained was purified by flash chromatography over silicagel using CHCl₃/MeOH (95/5-90/10-85/15) as the eluent to afford thetitled product 140 (1 g, 71.49%). ¹H NMR (300 MHz, DMSO-d₆+D₂O): δ1.70(s, 1H, COCH₃, minor rotamer (min)), 1.89 (s, 2H, COCH₃, major rotamer(maj)), 3.97-3.44 (m, 4H, H_(3′), H_(4′) & H_(5′)), 4.73(m, 1H, H_(2′)),6.26-6.08 (m, 2H, C₅H & H_(1′)), Anal. Calcd. for C₁₂H₁₆N₄O₇: C, 43.90;H, 4.91; N, 17.07 Found: C, 43.99; H, 5.06; N, 17.21.

Example 114 1-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)-5-fluorouracil(141)

[0275] A solution of 137 (1 g, 2.33 mmol) in saturated methanolicammonia (20 mL) was stirred in a steel bomb at room temperature for 16h. The steel bomb was cooled to 0° C., opened and evaporated to dryness.The residue was purified by flash chromatography over silica gel usingCHCl₃/MeOH (95/5-90/10-85/15) as the eluent to afford the titled product141 (0.6 g, 84.95%), ¹H NMR (300 MHz, (DMSO-d₆+D₂O): δ1.72 (s, 1.35H,COCH₃, minor rotamer (min)), 1.83 (s, 1.65H, COCH₃, major rotamer(maj)), 3.35-4.18 (m, 5H, H_(2′), H_(3′), H_(4′) & H_(5′)), 5.74 (d,0.45H, J=5.77 Hz, H_(1′), min), 5.84 (d, 0.55H, J=4.1 Hz, H_(1′), maj),8.25 (s, 0.45H, C₆H, min), 8.53 (s, 0.55H, C₆H, maj), 11.77 (bs, 1H, NH,exchangeable). Anal. Calcd. for C₁₁H₁₄FN₃O₆: C, 43.57; H, 4.65; N,13.86. Found: C, 43.40; H, 4.71; N, 13.80.

Example 115 1-(4′-Deoxy-4′-acetamido-β-L-ribofuranosyl)-5-fluorocytosine(142)

[0276] A solution of 138 (1 g, 2.33 mmol) in saturated methanolicammonia (20 mL) was stirred in a steel bomb at room temperature for 16h. The steel bomb was cooled to, opened and evaporated to dryness. Theresidue was purified by flash chromatography over silica gel usingCHCl₃/MeOH (95/5-90/10-85/15) as the eluent to afford the titled product142 (0.64 g, 90.70%). ¹H NMR (300 MHz, CD₃OD): δ1.92 (s, 2H, COCH₃,major rotamer (maj)), 2.17(s, 1H, COCH₃, minor rotamer (min)), 3.75-3.93(m, 2H, H_(5′)), 4.16-4.28 (m, 1.5H, H_(3′) & H_(4′)), 4.49 (t, 0.5H,J=4.4 & 4.94 Hz, H_(3′)), 4.65 (s, 1H, H_(2′)), 5.77 (d, 0.33H, J=5.22Hz, H_(1′), min), 6.11 (dd, 0.66H, J=1.92 & 4.12 Hz, H_(1′), maj), 8.19(d, 0.33H, J=6.86 Hz, C₆H, min), 8.66 (d, 0.66H, J=7.15 Hz, C₆H, maj).Anal. Calcd. for C₁₁H₁₅FN₄O₅: C, 43.71; H, 5.00; N, 18.54. Found: C,43.77; H, 5.17; N, 18.79.

[0277] It is to be understood that the above-described embodiments areillustrative only and that modifications thereof may occur to thoseskilled in the art. Accordingly, this invention is not to be regarded aslimited to the embodiments disclosed herein, but is to be limited onlyas defined by the appended claims.

We claim:
 1. A compound having a structure according to Formula I, inwhich the sugar is in an L conformation:

wherein: A is independently selected from N or C; B, C, E, F areindependently selected from CH, CO, N, S, Se, O, NR¹, CCONH₂, CCH₃, C—R²or P; R¹ is independently H, lower alkyl, lower alkylamines, COCH₃,lower alkyl alkenyl, lower alkyl vinyl or lower alkyl aryls. R² isindependently H, OH, halogens, CN, N₃, NH₂, C(═O)NH₂, C(═S)NH₂,C(═NH)NH₂.HCl, C(═NOH)NH₂, CC═NH)OMe, lower alkyl, lower alkylamines,lower alkyl alkenyl, lower alkyl vinyl, lower alkyl aryls or substitutedheterocycles; D is independently selected from CH, CO, N, S, Se, O, NR¹,CCONH₂, CCH₃, C—R², P or nothing, where R¹ is independently H, O, loweralkyl, lower alkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinylor lower alkyl aryls, and R² is independently H, OH, halogens, CN, N₃,NH₂, lower alkyl, lower alkylamines, lower alkyl alkenyl, lower alkylvinyl, lower alkyl aryls or substituted heterocycles. X is independentlyO, S, CH₂ or NR; where R is COCH₃; R₁ and R₄ are independently selectedfrom H, CN, N₃, CH₂OH, lower alkyl and lower alkyl amines; R₂, R₃, R₅,R₆, R₇ and R₈ are independently selected from H, OH, CN, N₃, halogens,CH₂OH, NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl, lower alkyl, loweralkyl amines and substituted heterocycles; and R₁, R₂, R₃, R₄, R₅, R₆,R₇ and R₈ are not all substituted at the same time; such that whenR₂═R₃═H, then R₇ and R₈ are hydrogens or nothing; when R₁, R₄ or R₅ aresubstituted, then R₇═R₈═H and R₂═R₃═OH; when R₂ or R₃ are substituted,then R₇ and R₈ are H or OH; when R₇ or R₈ are substituted, then R₂ andR₃ are H or OH; when R₇ and R₈ are hydroxyl, then R₂ and R₃ are not OH;when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH or C-substituted;F═CH; X═O, S or CH₂, then R₂ will not be H, OH, CH₃, halogens, N₃, CN,SH, SPh, CH₂OH, CH₂OCH₃, CH₂SH, CH₂F, CH₂N₃, aryl, aryloxy orheterocycles; when A═N; B═CO; C═N or NH; D═CO or C—NH₂; E is CH, C—CH₃or halogen; F═CH; X═N—COCH₃, then R₂ will not be H or OH; when A═N;B═CH; C═CH or CH₃; D═CH or C—CH₃; E is CH, C—CH₃ or C—CONH₂; F═CH; X═O,or CH₂, then R₂ will not be H or OH; when A═N; B═N, CO or CH; C═CH, C—Clor C—COCH₃; D═CH or C—Ph; E is CH, C—Cl or C—Ph; F═N or CO; X═O, then R₂will not be H or OH; when A═N; B═CO or CS; C═N or NH; D═CO or C—NH₂; Eis CH or N; F═N or CH; X═O, then R₂ will not be H or OH; and when A═C;B═CH; C═NH; D═CO, CS or C—NH₂; E is N or NH; F═CO or CH; X═O, then R₂will not be H or OH.
 2. A compound according to claim 1, further havinga structure according to Formula III.

wherein: X is independently O, S, CH₂ and NR, where R is COCH₃; R′ andR″ are independently selected from H, CN, C(—O)NH₂, NH₂, C(—S)NH₂,C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, heterocycles, halogens, loweralkyl or lower alkyl aryl; R₁ and R₄ are independently selected from H,CN, N₃, CH₂OH, lower alkyl or lower alkyl amines and; R₂, R₃, R₅, R₆, R₇and R₈ are independently selected from H, OH, CN, N₃, halogens CH₂OH,NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl, lower alkyl, lower alkylamines or substituted heterocycles; such that when R₂═R₃═H, then R₇ andR₈ are hydrogens or nothing. In compounds of Formula III, R′ ispreferably carboxamide or CN and R″ is hydrogen or halogens;R₁═R₄═R₅═R₇═R₈═II and R₂═R₃═OH, and preferably X is oxygen.
 3. Acompound according to claim 1, further having a structure according toFormula IV:

wherein: A is independently selected from N or C; B, C, E and F areindependently selected from CH, CO, N, S, Se, O, NR¹, CCONH₂, CCH₃, C—R²or P; R¹ is independently H, lower alkyl, lower alkylamines, COCH₃,lower alkyl alkenyl, lower alkyl vinyl or lower alkyl aryls. R² isindependently H, OH, halogens, CN, N₃, NH₂, C(═S)NH₂, C(═O)NH₂,C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, lower alkyl, lower alkylamines,lower alkyl alkenyl, lower alkyl vinyl, lower alkyl aryls or substitutedheterocycles; X is independently O, S, CH₂ or NR; where R is COCH₃; R₁and R₄ are independently selected from H, CN, N₃, CH₂OH, lower alkyl orlower alkyl amines; and R₂, R₃, R₅, R₆, R₇ and R₈ are independentlyselected from H, OH, CN, N₃, halogens, NH₂, CH₂OH, OCH₃, NHCH₃, ONHCH₃,SCH₃, SPh, alkenyl, allyl, lower aklyl, lower alkyl amines orsubstituted heterocycles; such that when R₂═R₃═H, then R₇ and R₈ arehydrogens or nothing; when A is carbon; B═E═N; C is N—Ph, then F is notCH; when A═N; C is CH; B═E═C—CH₃, then F is not nitrogen; and when A iscarbon, B═N; C═C—CONH₂; E═CH; F═S, then X is not CH₂. In compounds ofFormula IV, R¹ is preferably H, lower alkyl or allyl; R² is preferablyH, OH, halogens, CN, N₃, NH₂, C(═O)NH₂, C(═NH)NH₂.HCl, C(═NOH)NH₂ orC(═NH)OMe; and when R₁═R₄═R₅═R₇═R₈═H, then preferably R₂═R₃═OH andpreferably X is oxygen.
 4. A compound according to claim 1, furtherhaving a structure according to Formula V:

wherein: A is independently selected from N or C; B, C, E, F areindependently selected from CH, CO, N, S, Se, O, NR¹, CCONH₂, CCH₃, C—R²or P; R¹ is independently H, lower alkyl, lower aklylamines, COCH₃,lower alkyl alkenyl, lower alkyl vinyl or lower alkyl aryls. R² isindependently H, OH, halogens, CN, N₃, NH₂, C(═O)NH₂, C(═S)NH₂,C(═NH)NH₂.HCl, C(═NOH)NH₂, C(═NH)OMe, lower alkyl, lower alkylamines,lower alkyl alkenyl, lower alkyl vinyl, lower alkyl aryls or substitutedheterocycles; D is independently selected from CH, CO, N, S, Se, O, NR¹,CCONH₂, CCH₃, C—R², P or nothing; R¹ is independently H, O, lower alkyl,lower alkylamines, COCH₃, lower alkyl alkenyl, lower alkyl vinyl orlower alkyl aryls, R² is independently H, OH, halogens, CN, N₃, NH₂,lower alkyl, lower alkylamines, lower alkyl alkenyl, lower alkyl vinyl,lower alkyl aryls or substituted heterocycles; X is independently O, S,CH₂ or NR where R is COCH₃; R₁ and R₄ are independently selected from H,CN, N₃, CH₂OH, lower alkyl and lower alkyl amines; and R₂, R₃, R₅, R₆,R₇ and R₈ are independently selected from H, OH, CN, N₃, halogens,CH₂OH, NH₂, OCH₃, NHCH₃, ONHCH₃, SCH₃, SPh, alkenyl, lower alkyl, loweralkyl amines and substituted heterocycles; such that when R₂═R₃═H, thenR₇ and R₈ are hydrogens or nothing. when A═N; B═CO; C═N or NH; D═CO orC—NH₂; E is CH or C-substituted; F═CH; X═O, S or CH₂, then R₂ will notbe H, OH, CH₃, halogens, N₃, CN, SH, SPh, CH₂OH, Ch₂OCH₃, CH₂SH, CH₂F,CH₂N₃, aryl, aryloxy or heterocycles. when A═N; B═CO; C═N or NH; D═CO orC—NH₂; E is CH, C—CH₃ or halogen; F═CH; X═N—COCH₃, then R₂ will not be Hor OH; when A═N; B═CH; C═CH or CH₃; D═CH or C—CH₃; E is CH, C—CH₃ orC—CONH₂; F═CH; X═O, or CH₂, then R₂ will not be H or OH; when A═N; B═N,CO or CH; C═CH, C—Cl or C—OCH₃; D═CH or C—Ph; E is Ch, C—Cl or C—Ph; F═Nor CO; X═O, then R₂ will not be H or OH;